Isolated Colonic Histoplasmosis in Renal Transplant Recipient Post Covid-19 Infection

ABSTRACT

Introduction: Histoplasmosis is caused by the dimorphic fungus - Histoplasma capsulatum. The presentation of histoplasmosis is often disseminated, though primary intestinal involvement can rarely be seen in patients with cell mediated immune dysfunction like in patients with AIDS. We report a case of renal allograft recipient, who had history of COVID 19 infection and also underwent anti-rejection treatment for renal graft dysfunction, presented with chronic diarrhea and was diagnosed as a case of colonic histoplasmosis. Method(s) We report a case of 45 years old male who underwent renal transplant surgery one and a half year prior (February 2021) and was having stable graft function on tacrolimus, mycophenolate and steroid. He had history of fever and diarrhea in February 2022 and was diagnosed COVID-19 positive with RT-PCR, and was treated conservatively with intravenous dexamethasone and lowering of immunosuppressants. He had mild graft dysfunction in April 2022;renal graft biopsy had acute T-Cell mediated rejection (Banff Grade 1 B) and was treated with pulse steroids for 3 days. He had complaint of intermittent diarrhea, weight loss and intermittent fever since May 2022. He was evaluated and treated on outpatient basis with empirical oral antibiotics. He was admitted in June 2022 with complaint of high grade fever, loose stools leading to hypovolemic shock and renal dysfunction. He had marked thrombocytopenia and neutrophilic leukocytosis. He showed initial response to intravenous broad spectrum antibiotics and crystalloids, but intermittently symptoms of increased stool frequency and altered consistency were still persisting. Stool studies for ova, cyst, parasites and clostridium difficile were negative. Indian ink staining of stool sample had no evidence of Cryptococcosis. Serum PCR for cytomegalovirus was also negative. CT abdomen showed normal visualized bowel and other viscera. Upper GI endoscopy was unremarkable. Colonoscopy revealed multiple small ulcers with erythematous hue and clean base particularly in ceacum and along ascending colon. Multiple colonic biopsies were taken. Histopathology showed lymphoplasmacytic infilterate in the lamina propria. It also showed increased presence of foamy histiocytes, several of which also showed interacellular organism bearing a pseudocapsule. PAS stain also confirmed budding of these interacellular organisms which is consistent with Histoplasmosis. His HRCT chest revealed hyperinflated lungs, cylindrical bronchiectasis in left upper lobe. Urine for histoplasma antigenuria was negative. Result(s) He was treated with intravenous liposomal amphotericin B for initial two weeks followed by oral itraconazole. His symptoms responded remarkably to the treatment. In view of persisting thrombocytopenia and histoplasmosis his mycophenolate was stopped and tacrolimus was titrated as per trough levels Conclusion(s) Colonic histoplasmosis is associated with significant mortatlity and morbidity. Prolonged use of immunosuprresants, use of antirejection therapies (like high dose pulse methyl prednisolone and bortezomib) and even in some case reports COVID 19 infection have shown to increase the risk of histoplasmosis. Primary and isolated colonic histoplasmosis like in this case can be the atypical presentation which emphasizes the importance of maintaining a low threshold for consideration of histoplasmosis in renal allograft recipients. No conflict of interestCopyright © 2023