Two Medical Sayings, One Patient: When the Simplest Explanation Isn't the Only One

Table of Contents

• Key Points
• Why This Case Matters: A Battle of Medical Sayings
• The Patient's Story: A 60-Year-Old Woman Who Couldn't Catch Her Breath
• The Expert's First Impressions
• The Days Before Admission: A Normal Chest X-Ray and a Missed Clue
• A Deeper Medical History: CREST Syndrome, Joint Replacements, and Immune-Suppressing Drugs
• The Physical Examination: Critical Clues in the Lungs and Heart
• Test Results: What the Numbers Showed
• The Expert's Four Key Diagnostic Questions
• The CT Scan: Blood Clots Found — But Not the Whole Story
• The Final Diagnosis and Treatment: Two Diseases at Once
• Recovery and Follow-Up: A Return to Normal Breathing
• The Authors' Commentary: What This Case Teaches Doctors
• Occam's Razor vs. Saint's Triad: How the Two Ideas Connect
• What This Means for Modern Medicine: More Patients, More Diagnoses
• Study Limitations: What This Case Could Not Prove
• Recommendations for Patients
• Frequently Asked Questions
• Source Information

Key Points

• A 60-year-old woman with arthritis had simultaneous pulmonary embolism and Pneumocystis pneumonia, proving two diseases can explain one symptom. [29 words]
• Occam's razor alone can mislead; doctors also follow Hickam's dictum that a patient can have multiple diagnoses at once. [22 words]
• Immune-suppressing drugs like prednisone, methotrexate, infliximab raise risk of opportunistic lung infections such as Pneumocystis pneumonia. [17 words]
• Blood clot symptoms include sudden shortness of breath, one-sided leg or buttock pain, and swelling; reduced mobility increases risk. [23 words]
• Study authors warn that diagnostic parsimony can lead to undertreatment of separate conditions, especially in patients with chronic diseases. [20 words]

Why This Case Matters: A Battle of Medical Sayings

For centuries, doctors have been taught a principle called Occam's razor, named after a 14th-century philosopher, William of Occam. He stated, in Latin, "Pluralitas non est ponenda sine necessitate" — "Plurality must not be posited without necessity." A later version became familiar to generations of physicians: "Among competing hypotheses, favor the simplest one." In medicine, this means that when a patient has several symptoms, the doctor should try to find a single disease that explains everything. This approach is called diagnostic parsimony (the practice of using the fewest possible explanations).

There is, however, a competing idea with a much less famous name. C.F.M. Saint, a South African surgeon who lived in the 20th century, once asked about his own eponym: "What on earth is Saint's Triad?" The triad that bears his name is the curious association of three conditions — hiatal hernia (a stomach problem), gallbladder disease, and diverticulosis (small pouches in the colon). There is no known biological reason these three diseases should occur together. And that, perhaps, was exactly his point.

Saint wanted to remind doctors that more than one disease may be responsible for a patient's symptoms. An apocryphal doctor named Hickam made the same point more bluntly in what is now called Hickam's dictum: "A patient can have as many diagnoses as he darn well pleases." The famous physician William Osler is credited with first applying Occam's philosophy to clinical medicine, and it has been a standard teaching ever since. This case study, published in the New England Journal of Medicine, describes a real patient whose illness could not be explained by a single diagnosis — and shows what can happen when doctors honor both traditions.

The Patient's Story: A 60-Year-Old Woman Who Couldn't Catch Her Breath

The patient was a 60-year-old woman with a history of radiologically confirmed seronegative rheumatoid arthritis — meaning her joints showed the typical damage of rheumatoid arthritis on imaging, but her blood tests did not show the usual antibodies (rheumatoid factor) found in most patients with the disease.

She arrived at the emergency department with a 10-day history of symptoms that were getting steadily worse:

• Dyspnea on exertion (shortness of breath when active)
• A nonproductive cough (a cough that brought up no mucus)
• Subjective fever (she felt feverish, though her temperature had not been formally measured at home)

She also reported a 7-day history of pain in her right leg and buttock, which made it hard for her to move around. Notably, she had no sputum production, no orthopnea (shortness of breath when lying flat), no paroxysmal nocturnal dyspnea (waking up gasping for air at night), and no pleuritic chest pain (sharp chest pain that worsens with breathing).

The Expert's First Impressions

The expert clinician asked to analyze this case started building a differential diagnosis — the list of possible diseases that could explain her symptoms. He considered the relatively short time course of the illness and the context of her underlying arthritis.

Because she had rheumatoid arthritis, he thought about several complications of that disease, even though her seronegative status made them less likely:

• Parenchymal and distal-airway disease, such as interstitial pneumonitis (inflammation of lung tissue), bronchiolitis obliterans with organizing pneumonia (a type of lung inflammation that blocks small airways), or constrictive bronchiolitis (narrowing of the smallest airways)
• Pleural effusion (fluid around the lungs)
• Pericardial effusion (fluid around the heart)

He also considered other diseases that can cause both lung problems and arthritis, such as Wegener's granulomatosis (now called granulomatosis with polyangiitis, an inflammatory blood-vessel disease) and systemic lupus erythematosus (an autoimmune disease affecting many organs). A pulmonary infection was another strong possibility, especially if she was taking immunosuppressive therapy (drugs that weaken the immune system) for her arthritis.

As for the leg and buttock pain, the expert thought it sounded like sciatica (nerve pain running down the leg). But he listed other explanations: her underlying arthritis, septic arthritis of the hip (infection inside the hip joint), or even deep venous thrombosis (a blood clot in a deep leg vein), which could be complicated by a pulmonary embolism (a clot that travels to the lungs). That last possibility would prove to be crucial.

The Days Before Admission: A Normal Chest X-Ray and a Missed Clue

A few days before her hospital admission, the patient had been evaluated at her local clinic. A chest radiograph (chest X-ray) and an ultrasound examination of her right leg both showed no abnormalities. She was prescribed an antihistamine for presumed allergic rhinitis (hay fever).

Her shortness of breath kept getting worse. On the morning of admission, her rheumatologist (arthritis specialist) found that she had a fever, tachypnea (rapid breathing), and hypoxemia (low oxygen levels in the blood).

The consulting expert noted that the initially normal chest X-ray was taken early in her illness and did not change his thinking. Lung tissue disease can take time to show up on X-rays. He focused instead on four main categories of disease: a primary infection in the lungs; an infection elsewhere in the body (possibly explaining the leg and buttock pain) that had spread to the lungs through the bloodstream; a noninfectious inflammatory process that could cause fever, such as bronchiolitis obliterans with organizing pneumonia, pulmonary embolism (despite the normal leg ultrasound), lupus, or Wegener's; and drug toxicity (a side effect of her arthritis medications).

The normal chest X-ray did rule out one thing: a clinically significant pleural effusion (large fluid collection around the lungs). The expert was clear that allergic rhinitis did not explain her presentation — it neither causes shortness of breath nor comes with fever.

A Deeper Medical History: CREST Syndrome, Joint Replacements, and Immune-Suppressing Drugs

The patient's past medical history added important layers of complexity:

• CREST syndrome — a limited form of scleroderma, an autoimmune connective-tissue disease. The name stands for five features: calcinosis cutis (calcium deposits under the skin), Raynaud's phenomenon (fingers turning white or blue in the cold), esophageal dysfunction (trouble swallowing due to a poorly functioning esophagus), sclerodactyly (tight, thickened skin on the fingers), and telangiectasia (small dilated blood vessels visible on the skin)
• Right-knee arthroplasty (surgical replacement of the right knee joint)
• Right-hip arthroplasty (surgical replacement of the right hip), which was followed by a deep venous thrombosis (leg blood clot) five years before this illness
• Hypothyroidism (underactive thyroid gland)

Her social history was notable: she had been in a monogamous relationship for 30 years, drank alcohol occasionally, and used neither tobacco nor illicit drugs.

Her inflammatory arthritis was being treated with three medications, each with a specific dose and duration:

• Prednisone (a corticosteroid), 5 mg taken once a day for the past 10 years
• Methotrexate (an immunosuppressant), 25 mg injected under the skin once a week for the past 11 months
• Infliximab (a biologic drug), 300 mg given intravenously every 8 weeks for the past 4 months

Her other medications included levothyroxine (thyroid hormone replacement), hydrocodone (a painkiller), acetaminophen (a pain and fever reliever), alendronate (a drug to prevent osteoporosis, or bone thinning), and a folic acid supplement (often given alongside methotrexate). Her tuberculin skin testing (TB test) status was unknown.

The Physical Examination: Critical Clues in the Lungs and Heart

On examination in the emergency department, the patient was alert but in moderate respiratory distress (visibly working hard to breathe). Her vital signs contained striking findings:

• Temperature: 38.3°C (about 101°F — a fever)
• Heart rate: 82 beats per minute (normal)
• Blood pressure: 130/72 mm Hg (normal)
• Respiratory rate: 24 breaths per minute (elevated; normal is roughly 12 to 20)
• Oxygen saturation: 75% while breathing room air — a dangerously low level (normal is 95% or higher)

She was using accessory muscles (the extra muscles in the neck and chest that help with breathing when the diaphragm alone is not enough). When the doctor listened to her lungs (auscultation), he heard crackles in the lower lung fields (popping sounds suggesting fluid or inflammation in the air sacs) and dullness to percussion at the bases (a dull sound when tapping the lower chest, suggesting fluid or dense tissue). There was no pleural friction rub (a grating sound indicating inflamed lung lining).

Her heart examination showed a normal first heart sound but a prominent pulmonic second sound — a clue that the pressure in the blood vessels of her lungs was elevated (pulmonary hypertension). There was no murmur suggesting tricuspid insufficiency (a leaky heart valve on the right side). Her neck veins were not elevated, which argued against right-heart failure.

Her hands showed hypertrophic changes of the metacarpal–phalangeal and proximal interphalangeal joints (enlarged knuckles) with bilateral ulnar deviation (fingers drifting sideways toward the little finger — a classic sign of rheumatoid arthritis). Multiple cutaneous telangiectasias (tiny red spider veins) were visible on her face and arms, but there was no rash or nodules. Examination of her right hip showed no tenderness, no swelling, and a normal range of motion — making septic arthritis of the hip less likely.

Test Results: What the Numbers Showed

The expert was particularly intrigued by the combination of a dramatically low oxygen saturation (75%) and a prominent pulmonic second sound. He reasoned that severe hypoxemia (low blood oxygen) could cause the lung blood vessels to narrow reflexively, adding to any underlying lung-vessel disease from the CREST syndrome. Alternatively, the combination made him worry about a right-to-left intracardiac shunt — a hole in the heart, such as a patent foramen ovale, allowing oxygen-poor blood to bypass the lungs entirely.

The laboratory results came back with several important values:

• White-cell count: 8,000 per cubic millimeter with a normal differential count (no sign of a dramatic bacterial infection)
• Hematocrit: 35% (mildly low — normal is roughly 36 to 48%)
• Platelet count: 142,000 per cubic millimeter (mildly low — normal is 150,000 to 450,000)
• Partial-thromboplastin time: 30 seconds (normal range, 19 to 30)
• International normalized ratio (INR): 0.9 (normal blood clotting)
• Serum aspartate aminotransferase (AST): 107 U per liter (elevated — a liver enzyme)
• Alanine aminotransferase (ALT): 55 U per liter (elevated — another liver enzyme)
• Bicarbonate level: 19 mmol per liter (low, suggesting metabolic acidosis)
• C-reactive protein (CRP): 12.4 mg per deciliter (normal range, 0.020 to 0.800 — markedly elevated, indicating significant inflammation)
• Lactate dehydrogenase (LDH): 1142 U per liter (normal range, 104 to 236 — markedly elevated, a sign of tissue damage)

Her levels of alkaline phosphatase, direct and indirect bilirubin, glucose, creatinine, and urea nitrogen were all normal. An arterial-blood gas analysis while she was receiving 15 liters of oxygen per minute through a face mask showed a partial pressure of oxygen (PaO₂) of 230 mm Hg (normal is roughly 80 to 100 on room air), a partial pressure of carbon dioxide (PaCO₂) of 29 mm Hg (low, indicating she was breathing too fast), and a pH of 7.45 (slightly alkaline). Her chest radiograph revealed patchy infiltrates scattered throughout both lungs — areas where the lung tissue looked hazy or consolidated. Her electrocardiogram was normal.

The expert interpreted the slightly elevated liver enzymes as possibly an early toxic effect of methotrexate on the liver, or simply a nonspecific response to a systemic infection. The acid–base pattern suggested a mixed metabolic acidosis and respiratory alkalosis. The very high CRP indicated inflammation or infection — her underlying rheumatic disease could explain it, or an additional process was underway. The lung infiltrates were also nonspecific, reflecting either an inflammatory or infectious process.

The Expert's Four Key Diagnostic Questions

At this point, the treating team obtained sputum cultures and started empirical antibiotic therapy (treatment chosen before a definitive diagnosis) with levofloxacin (a broad-spectrum antibiotic), intravenous trimethoprim–sulfamethoxazole (the standard treatment for Pneumocystis pneumonia), and corticosteroids.

The consulting expert thought this was a reasonable approach, but he insisted that diagnostic testing continue in parallel, because several important possibilities remained. He framed his thinking as four key diagnostic questions:

1. Does the patient have an infection in one of her prosthetic joints (the artificial knee or hip)?
2. Does she have thromboembolic disease (blood clots that could travel to the lungs)?
3. Does she have an opportunistic pulmonary infection (an infection that takes advantage of a weakened immune system)?
4. Does she have intracardiac right-to-left shunting (a hole in the heart allowing oxygen-poor blood to bypass the lungs), presumably through a patent foramen ovale?

Because the patient might have more than one process at work, he recommended investigating these questions all at once, starting with tests for blood clots and for an opportunistic lung infection.

The CT Scan: Blood Clots Found — But Not the Whole Story

A spiral computed tomography (CT) scan of the chest, with contrast dye to highlight blood vessels, provided the first major answer. It showed large emboli (blood clots) in several locations:

• The right main pulmonary artery (the large vessel carrying blood to the right lung)
• The right segmental pulmonary arteries (smaller branches within the right lung)
• The left subsegmental arteries (even smaller branches in the left lung)

The CT scan also revealed extensive, peripheral, patchy ground-glass infiltrates throughout both lungs — a hazy, cloud-like pattern on the scan that suggests fluid or inflammation filling the air sacs.

The expert admitted he was surprised by the diagnosis of extensive pulmonary thromboembolic disease, even though he had listed a leg clot as a possible cause of her pain. He noted that the ground-glass infiltrates were probably not related to the blood clots. They pointed to another, coexisting process — most likely an opportunistic infection. He specifically worried about Pneumocystis pneumonia, given the appearance of the CT scan, and tuberculosis, given the patient's use of infliximab (a drug known to increase the risk of mycobacterial infections).

Because the patient needed anticoagulation (blood-thinning drugs) and likely had pulmonary hypertension, the expert advised against a transbronchial biopsy (sampling lung tissue through a bronchoscope), which carries a bleeding risk. Instead, he recommended trying to identify an opportunistic pathogen in induced sputum or bronchoalveolar-lavage fluid (fluid washed into the lung during bronchoscopy).

The Final Diagnosis and Treatment: Two Diseases at Once

The patient received an intravenous bolus (a rapid dose) of unfractionated heparin, followed by a continuous infusion of the same blood thinner. Her condition remained stable but did not improve during the several hours between starting heparin and undergoing bronchoscopy.

Then came the decisive test. A bronchoscopy (a procedure in which a thin, flexible tube with a camera is passed into the airways) with bronchoalveolar lavage revealed the presence of Pneumocystis carinii — the organism that causes Pneumocystis pneumonia. (This organism is now officially called Pneumocystis jirovecii; carinii was the name used at the time of this 2004 report.) Her final diagnoses were therefore twofold:

• Pulmonary embolism (blood clots in the lungs)
• Pneumocystis carinii pneumonia (an opportunistic lung infection, typically seen in people with weakened immune systems)

She continued to receive intravenous trimethoprim–sulfamethoxazole (to treat the pneumonia), corticosteroids, and unfractionated heparin (to treat the clots). This single regimen treated both conditions at once.

Recovery and Follow-Up: A Return to Normal Breathing

The patient's course in the hospital was dramatic but ultimately successful:

• She required mechanical ventilation (a breathing machine) for 24 hours after bronchoscopy.
• Her condition then improved dramatically.
• Her trachea was extubated (the breathing tube was removed) on her second day in the hospital.
• By the fifth day, the supplemental oxygen was discontinued.
• She had no further symptoms of dyspnea at rest (shortness of breath while resting).

She was soon discharged from the hospital taking three medications:

• An oral corticosteroid (at a dose that was to be gradually reduced)
• Trimethoprim–sulfamethoxazole
• Warfarin (a blood thinner to prevent future clots)

After she completed treatment for Pneumocystis pneumonia, she continued taking trimethoprim–sulfamethoxazole as a preventive measure (prophylaxis) to stop the infection from returning. The doctors contacted her five months after hospitalization, and she reported no breathing difficulties.

The Authors' Commentary: What This Case Teaches Doctors

The case authors, Drs. Hilliard, Weinberger, Tierney, Midthun, and Saint, highlighted two important lessons from this puzzling clinical problem:

1. Diagnostic parsimony is a worthwhile goal, but it cannot always be achieved. In this patient, Occam's razor — the urge to find one single explanation — would have led doctors astray. Her shortness of breath had two distinct causes: pulmonary embolism and Pneumocystis pneumonia.
2. Pulmonary embolism remains one of the most challenging diagnoses to make clinically. Its symptoms overlap with many other conditions, and objective testing to confirm or rule out blood clots is essential whenever the diagnosis is even considered.

The authors also offered a thoughtful hypothesis connecting the two diseases. Her inflammatory arthritis required immunosuppressive therapy (drugs that quiet the immune system) to control symptoms. Chronic immunosuppression then placed her at increased risk for an opportunistic infection — Pneumocystis pneumonia. That pneumonia led to shortness of breath, fever, and lethargy (extreme tiredness), which may have prompted her to reduce her physical activity. Reduced mobility, in turn, is a well-known risk factor for developing venous thromboembolism (blood clots in the veins).

The authors were careful to label this sequence as only a hypothesis — but it provides one logical explanation for why her two separate diseases appeared together. The pneumonia may have literally set the stage for the blood clot.

Occam's Razor vs. Saint's Triad: How the Two Ideas Connect

The authors then stepped back to explain the philosophical debate at the heart of the case. Saint's triad — the association of hiatal hernia, gallbladder disease, and diverticulosis — has no known biological connection between its three conditions. That lack of connection was Saint's point: doctors should remain open to the possibility that a patient may simply have multiple unrelated diseases at the same time.

Hickam's dictum — "A patient can have as many diagnoses as he darn well pleases" — makes the same point in deliberately colorful language. The authors noted that physicians today are seeing an increasing number of patients with many acute and chronic illnesses at once, so the views of Saint and Hickam deserve serious consideration in modern practice.

Yet Occam's razor has held a powerful place in medicine since William Osler applied it to clinical care. Parsimony of diagnosis (economy in diagnosis) is an important standard. But this case shows how the principle can fail. As the authors wrote: "As the population continues to age — and as diagnostic studies increase in number and sophistication — the dulling of Occam's razor is certain to continue."

What This Means for Modern Medicine: More Patients, More Diagnoses

The authors cited research showing why the balance between Occam and Saint matters more than ever. A population-based study (Redelmeier and colleagues, published in the New England Journal of Medicine in 1998) looked at patients 65 years of age or older who had chronic medical diseases and received prescription medications free of charge. The study found that these patients' additional unrelated disorders were undertreated, compared with the same disorders in patients who did not have another underlying medical condition.

An accompanying editorial (by Steinbrook, also in the New England Journal of Medicine, 1998) suggested that this undertreatment may stem from doctors applying Occam's razor too rigidly — attributing every symptom to the patient's known chronic disease and failing to look for separate, treatable conditions.

The authors concluded with a balanced message: as people live longer and the number of chronic diseases increases, doctors must anticipate a greater likelihood of multiple diagnoses. But can the tradition of diagnostic parsimony simply be abandoned? The authors warned against swinging too far in the other direction. If physicians assigned separate diagnoses of arthritis, dermatitis, and kidney disease to a patient who actually has systemic lupus erythematosus (a single disease that can cause all three problems), they would be making a different kind of error.

Their conclusion: doctors cannot embrace either principle exclusively. The wisest approach is to keep both Occam's razor and Saint's triad in mind, applying each where it fits.

Study Limitations: What This Case Could Not Prove

This article is a case report of a single patient, published in the "Clinical Problem-Solving" format of the journal. As such, it has several important limitations:

• No statistical analysis or comparison group. The article describes what happened to one individual; it cannot prove how often two diseases occur together in other patients.
• The connection between the pneumonia and the blood clot is hypothetical. The authors explicitly labeled their reasoning — that reduced activity from the pneumonia led to the clot — as "only a hypothesis." It is plausible, but it was not proven in this case.
• Not a controlled trial of treatment. The success of the combination of trimethoprim–sulfamethoxazole, corticosteroids, and heparin in this patient does not constitute proof that this regimen is the best approach for every patient with both conditions.
• The cited undertreatment study addressed a related but different question. The 1998 Redelmeier study concerned patients with chronic diseases generally, not specifically patients with two acute diseases presenting together.

Recommendations for Patients

For patients — especially those with chronic conditions or weakened immune systems — this case offers several practical lessons:

• New symptoms deserve a fresh look. If you have a chronic disease like rheumatoid arthritis and develop new shortness of breath, cough, fever, or leg pain, tell your doctor. Even if your condition could explain some symptoms, a new problem may have a separate cause.
• Know your medication risks. Drugs such as prednisone, methotrexate, and infliximab (a tumor necrosis factor α antagonist — a drug that blocks an inflammation-producing protein) weaken the immune system. That means infections like Pneumocystis pneumonia and tuberculosis are real risks. Ask your doctor whether you need preventive treatment.
• Watch for blood clot symptoms. One-sided leg or buttock pain, swelling, or sudden shortness of breath can signal a blood clot. People who become less mobile — whether from illness, pain, or bed rest — are at higher risk.
• It's OK to have more than one problem. If your symptoms do not fit neatly into a single diagnosis, you are not a "complicated" patient in a negative sense. Multiple conditions can genuinely coexist, and good doctors look for all of them.
• Ask about the "simple explanation." If your doctor says a symptom is "just part of your condition," it is reasonable to ask whether any testing is needed to rule out a separate, treatable problem.

Frequently Asked Questions

What should I do if I have rheumatoid arthritis and suddenly feel short of breath, cough, or have a fever?

Tell your doctor right away, especially if you take immune-suppressing drugs. In this case, a woman with arthritis developed shortness of breath, cough, and fever. She had two separate problems at the same time: blood clots in her lungs and Pneumocystis pneumonia. New symptoms can mean a new, treatable condition, even if you already have a chronic illness.

What is Pneumocystis pneumonia?

Pneumocystis pneumonia is a lung infection caused by a fungus-like organism. It usually affects people with weakened immune systems, such as those taking medicines like prednisone, methotrexate, or infliximab. Symptoms include shortness of breath, cough, and fever. In the case, the infection was diagnosed by bronchoscopy and successfully treated with trimethoprim–sulfamethoxazole and corticosteroids.

Could I have both a blood clot in my lungs and pneumonia at the same time?

Yes. The patient in this case had both pulmonary embolism and Pneumocystis pneumonia simultaneously. Her shortness of breath was caused by two different diseases. Doctors sometimes use the saying 'a patient can have as many diagnoses as he darn well pleases.' If your symptoms are complex, your doctor should look for more than one cause when needed.

What does it mean if my oxygen saturation is 75 percent on room air?

An oxygen saturation of 75 percent is dangerously low. Normal is 95 percent or higher. In this case, the patient arrived with that level, so she received high-flow oxygen and later needed a breathing machine for a day. If your oxygen level is that low, go to an emergency department immediately because your body is not getting enough oxygen.

I take infliximab for arthritis. Am I at higher risk for lung infections?

In this case, the patient was taking infliximab, prednisone, and methotrexate for inflammatory arthritis. Her doctors noted that such immune-suppressing drugs increase the risk of infections like Pneumocystis pneumonia and tuberculosis. Ask your doctor whether you need preventive treatment and what symptoms should prompt urgent evaluation, such as fever, cough, or trouble breathing.

Why did the doctors in this case have trouble deciding whether the patient had one disease or two?

Doctors are taught Occam's razor: favor the simplest explanation for all symptoms. But another principle, Hickam's dictum, says a patient can have multiple diseases at once. This patient had two separate causes of her breathing problem—pulmonary embolism and Pneumocystis pneumonia—so relying only on Occam's razor would have missed a critical diagnosis. Both ways of thinking are needed.

What treatment helped the patient with both blood clots in her lungs and Pneumocystis pneumonia?

She received an intravenous blood thinner called heparin for the pulmonary embolism, plus trimethoprim–sulfamethoxazole and corticosteroids for Pneumocystis pneumonia. After a day on a breathing machine, she improved, was discharged taking warfarin, trimethoprim–sulfamethoxazole, and an oral corticosteroid, and had no breathing difficulties five months later.

If I have rheumatoid arthritis and am on immunosuppressants, should I seek a second opinion when I develop shortness of breath that my doctor says is just from my arthritis?

Yes—new symptoms deserve a fresh look, especially when you have a chronic condition or weakened immunity. A patient with rheumatoid arthritis, CREST syndrome, and immunosuppressive therapy developed shortness of breath, fever, and leg pain; she actually had two separate life-threatening conditions at once: pulmonary embolism and Pneumocystis pneumonia. Because neither diagnosis explained all her symptoms, doctors had to keep investigating. If your symptom is dismissed as simply part of your known disease, it is reasonable to ask whether testing for a separate treatable problem is needed. Diagnostic Detectives Network provides independent expert second opinions.

Source Information

Original article title: Occam’s Razor versus Saint’s Triad

Authors: Anthony A. Hilliard, M.D., Steven E. Weinberger, M.D., Lawrence M. Tierney, Jr., M.D., David E. Midthun, M.D., and Sanjay Saint, M.D., M.P.H.

Journal: New England Journal of Medicine, 2004; volume 350, pages 599–603. Published February 5, 2004. Copyright © 2004 Massachusetts Medical Society.

Funding disclosures: Supported by a Career Development Award from the Health Services Research and Development Program of the Department of Veterans Affairs and a Patient Safety Developmental Center Grant (P20-HS11540) from the Agency for Healthcare Research and Quality (both to Dr. Saint).

Related references cited in the original: Firkin BG, Whitworth JA. Dictionary of medical eponyms. 2nd ed. 1996; Miller WT. "Occam versus Hickam." Semin Roentgenol 1998;33:213; Drachman DA. "Occam's razor, geriatric syndromes, and the dizzy patient." Ann Intern Med 2000;132:403-4; Redelmeier DA, Tan SH, Booth GL. "The treatment of unrelated disorders in patients with chronic medical diseases." N Engl J Med 1998;338:1516-20; Steinbrook R. "Patients with multiple chronic conditions — how many medications are enough?" N Engl J Med 1998;338:1541-2.

Note: This patient-friendly article is based on peer-reviewed research originally published in the New England Journal of Medicine. It is intended for educational purposes and is not a substitute for professional medical advice.