Disseminated histoplasmosis in an urban canine with access to the rural environment

Résumé

Histoplasmosis is a systemic disease caused by the fungus Histoplasma capsulatum. The microorganism causes localized granulomatous disease, with the respiratory tract being most affected, and can spread through the lymphatic and blood stream. Severe infection in dogs is associated with immunosuppressive therapies. The reported case occurred in a canine, brought to care with a serious clinical condition, which did not respond to treatment and was euthanized. The necropsy examination showed white nodules, of firm consistency and distributed throughout the omentum, liver, splenic capsule, pancreas, stomach serosa, intestines, bladder, mesenteric and inguinal lymph nodes, diaphragm, parietal pleura, aorta and aortic lunate. Microscopically, all nodular lesions consisted of areas of necrosis, with intense histiolymphoplasmacytic infiltrate, epithelioid macrophages and Langhans-type giant cells with yeast-like structures, with morphology and arrangement consistent with Histoplasma spp., confirmed by special Periodic Acid-Schiff (PAS) stains and Grocott. Therefore, the present study aims to describe a case of multisystemic histoplasmosis in a canine, diagnosed through anatomopathology and histochemistry, and to alert to this potential infection in urban canines with access to rural areas and/or environments with the fungal agent.