Clinico- pathological conference Extrapulmonary tuberculosis masking disseminated histoplasmosis in AIDS

Case presentation (Dr L Greene and Dr A L Pozniak) A 32 year old black African man was admitted from our emergency clinic complaining of right sided abdominal pain which was dull in nature with colicky exacerbations that had been present for 6 weeks. The pain had increased in severity over the preceding 3 days. The patient also reported watery diarrhoea and weight loss of 7 kg over the same period. He had been found to be HIV antibody positive 1 month previously following an episode of shingles. He reported no risk factors for HIV infection other than unprotected vaginal intercourse in Africa up to 7 years previously. He had no other significant medical history and had not travelled outside of Europe since leaving west Africa in 1990. His CD4 count at diagnosis was less than 20 cells ×10/l. His only medication at presentation was co-trimoxazole 960 mg three times weekly as primary prophylaxis against Pneumocysitis carinii pneumonia and co-proxamol for pain relief. On examination he was thin and mildly pyrexial at 37.5°C. Scarring from his recent attack of shingles was present on the left anterior thigh in the distribution of the L2 dermatome. The oral cavity was clear. Bilaterally, shotty, non-tender lymph nodes were present in the cervical, axillary, and inguinal regions. There were no cardiovascular or respiratory abnormalities. In the abdomen he had a large, tender, irregular non-mobile right iliac fossa mass that was dull to percussion which extended from the pelvis to below the level of the umbilicus. No other masses were palpable. Neurological examination was unremarkable. Baseline investigations showed the haemoglobin was 10.7 g/dl, total white cell count was 3.2 × 10/l, and platelet count was 122 × 10/l. The mean cell volume was low at 75 fl with a ferritin level within normal limits. The aspartate aminotransferase (AST) and albumin were abnormal at 75 IU/l (normal range 0–37 IU/l) and 29 g/l (normal range 33–47 g/l) respectively, and the rest of the blood biochemistry was otherwise unremarkable. Bacterial and mycobacterial blood cultures, serum cryptococcal antigen, and blood, urine, and throat specimens for cytomegalovirus early antigen detection were all performed. Stool was examined for the presence of bacterial pathogens, ova cysts and parasites, and Clostridium diYcile toxin. Cysts of Cryptosporidium parvum were detected, but all other microbiological investigations were negative. A chest radiograph was normal. An abnormal bowel gas pattern in the region of the mass was seen on a supine abdominal film. A computed tomograph (CT) scan of the abdomen and pelvis demonstrated a mass apparently comprising matted loops of distal ileum and lymph nodes (fig 1). Hepatomegaly, moderate splenomegaly, and mesenteric and retroperitoneal lymphadenopathy were also noted. Barium studies were performed in order to better define the mass. These confirmed that the mass involved the distal ileum and caecum and showed an ileocolic fistula. An ultrasound guided percutaneous needle biopsy of the mass was performed. Histological examination of the material obtained was reported as showing lymph node tissue containing areas of granulomatous inflammation in association with acid and alcohol fast bacilli. The presence of a single yeast was questioned but not confirmed. A CT guided attempt to obtain a further specimen from the mass was unsuccessful. On the basis of these findings a diagnosis of abdominal tuberculosis was made and antituberculous therapy was initiated with rifampicin, isoniazid, ethambutol, and pyrazinamide in conventional doses. In view of the patient’s weight loss and poor caloric intake, a feeding gastrostomy was inserted percutaneously. Over the course of the following 7 days a marked reduction in the size and tenderness of the abdominal mass was observed which was paralleled by resolution of the patient’s fever. He was discharged from hospital and at outpatient review 2 and 4 weeks later, further improvements in symptoms and signs were reported. Eight weeks after discharge the patient reattended the emergency clinic at which time he was complaining of intermittent high fevers, sweats, and watery diarrhoea. He had also developed an itchy rash on his right shoulder. He was adamant that he had adhered to the antituberculous therapy.