werner@aecom.UUCP (Craig Werner) (01/25/86)
<<>> [An uncharacteristically long differential, but I realized I was treading on tricky ground with this one. Comments?] > > A 27-old Hispanic female from the South Bronx is referred to clinic > with a 2-week history of dry cough, fever, shortness of breath, and weight > loss. On physical exam, she has a temperature of 102. An examination of her > head reveals oral thrush (an infection of the mouth by the yeast Candida). > Because of her extreme difficulty breathing, she is admitted to the > hospital. An admission chest X-ray reveals is diffusely cloudy on both sides, > suggesting interstitial pneumonia. Routine blood test shows mild anemia (low > hematocrit) and a White Blood Cell count in the low normal range. > > What is the suspect diagnosis? Oral Thrush (Candida) is diagnostic of a prounounced Cell-mediated Immune Suppression. (It also occurs during the use of broad-spectrum antibiotics which eliminate native flora - and the mouth is an exceptional dirty place, so there are a lot of native flora to eliminate.) Anemia is a non-specific sign of either malnutrition or chronic disease, but can also occur independently or related to specific diseases. The white blood cell count is in the normal range. But given a Pneumonia, one would expect it to be elevated. So, seeing it in the normal range is akin to seeing it depressed. This is in agreement with the findings of oral thrush. What causes Cell-mediated immune suppression: Steroids - most commonly given for treatment of certain illnesses (iatrogenic immune suppression) but also can occur in Ovarian and Adrenal tumors, which can produce large amounts of Steroids (moreso Adrenal), or in Pituitary (Brain) Tumors, which stimulate the Adrenals by releasing the hormone ACTH. Note: Physical stress also causes release of ACTH, but the immune suppression is rarely quite this severe. Cancer - many kinds of cancer can cause both anemia (Red Blood Cell) and immune suppression (White Blood Cell decrease). In a young woman, Hodgkin's Disease, non-Hodgkin's Lymphoma, and Leukemia are the most commonly encountered Cancers. In the past, there would be an extensive workup looking for possible tumors. Now, the first step is a careful examination of the extremities, (What are we looking for? SEE BELOW.) or a careful sexual history. The Pneumonia: Pneumonias come in three types: Bacterial, Viral, and Fungal. Bacterial is what is generally thought of as Pneumonia classicly, and it causes the classic consolidation of lung into solid fluid and pus, visible as white on X-ray. Viral is more common in healthy people, and is self-limiting, although may cause breathing problems so bad during its course that hospitalization is necessary. This is called ARDS (Adult Respiratory Distress Syndrome). Fungal is only seen in immune suppressed patients or secondarily to TB. It's course is generally bad, not because the organism is virulent, but because the only people who get such pneumonias are dreadfully ill to begin with. A spotty interstitial type of pneumonia would be viral or fungal, or even miliary Tuberculosis (not common since the 1950s in this country) As it turned out, the patient's pneumonia was caused by the organism Pneumocystis Carinii, a protozoan. This too is seen only in immunosuppressed patients. THE DIAGNOSIS: Admitted for: ARDS (caused by Pneumocystis Carii) Underlying Condition: AIDS (Acquired Immune Deficiency Syndrome) As I noted above, examination of the extremities revealed significant needle tracks, but the hint stated that she had been referred from Methadone maintenance. Hence, she falls into the Intravenous Drug User Risk Group. Confirming the Diagnosis: #1 A differential White Blood Count was done was which revealed an inverted T4/T8 ratio (T4/T8 = 0.2) with low absolute T4 numbers Explanation: T4 cells are helper cells. T8 are both Suppressor Cells and Killer Cells (probably two cell types, but no one's yet been able to tease them apart) The ratio can be inverted because of two reasons: 1) Less Helper and More Suppressor, or 2) Simply more Killer T8s, which happens in many illnesses, but in which T4 count is normal or elevated. #2 An Enzyme-linked Immunosorbent Assay (ELISA) was performed on the patient's blood, and was positive for Antibody to HTLV-3. I took a lot of time to explain this one, because two people wrote me that they had those symptoms. It was an abbreviated description, and I don't want them to think "Oh no, I've got AIDS." Perhaps this long differential also gave you some insight into the workings of the medical model. [Feedback, anyone?] -- Craig Werner !philabs!aecom!werner "...if that's the hand you use, well, nevermind..."