Primary Pulmonary Mycobacteriosis in a Cat: Immunohistochemical and Histopathological Evaluation

Abstract

In this case report, primary pulmonary mycobacteriosis in a domestic cat was assessed using histopathological and immunohistochemical methods. The cat was admitted to a private veterinary clinic and presented with hyporexia, lethargy, and dyspnea with an abdominal component. For diagnostic purposes, thorax radiography was performed. Radiographic lung imaging showed the presence of opaque foci that were widely distributed throughout the lung. The cat’s condition gradually deteriorated, and the cat died 2 hours after being brought to the clinic. Following owner consent, gross post-mortem examination was performed immediately after death at the same clinic. White foci measuring 2–10 mm in diameter covered the surface of the lungs and were present throughout the parenchyma, mostly multifocally and occasionally coalesc­ing. No other macroscopical pathological findings were observed in other organs or on the skin. Some of the lung tissue with macroscopic lesions underwent further histo­pathological and immunohistochemical examination. Multifocal to coalescing areas of caseous necrosis (without a fibrous capsule) with, karyorrhectic nuclei, and numerous macrophages were observed. Ziehl-Neelsen staining revealed many acid-fast bacteria. Immunohistochemical staining revealed positive immunostaining for Mycobacterium spp. This case study highlights the importance of considering zoonotic risks in cats diagnosed with primary pulmonary mycobacteriosis. Primarna pljučna mikobakterioza pri mački: imunohistokemična in histopatološka ocena Izvleček: V tem poročilu o primeru je bila ocenjena primarna pljučna mikobakterioza pri domači mački z uporabo histopatoloških in imunohistokemičnih metod. Mačka je bila sprejeta v zasebno veterinarsko kliniko zaradi simptomov hiporeksije, letargije in dispneje z abdominalno komponento. Za diagnostične namene je bila opravljena rentgenska preiskava prsnega koša, ki je pokazala prisotnost motnih žarišč, široko razporejenih po pljučih. Stanje mačke se je posto­poma slabšalo, umrla je dve uri po prihodu v kliniko. Po privolitvi lastnika je bila takoj po smrti opravljena raztelesba. Bela žarišča, premera od 2 do 10 mm, so prekrivala površino pljuč. Prisotna so bila po celotnem parenhimu večinoma multifokalno in mestoma zlivajoče. V drugih organih in na koži ni bilo opaznih drugih makroskopskih patoloških sprememb. Nekatere dele pljučnega tkiva z makroskopskimi spremembami smo dodatno histopatološko in imunohistokemično pregledali. Opazili smo multifokalna do zlivajoča se območja kazeozne nekroze (brez fibrozne kapsule) s karioznimi jedri in številnimi makrofagi. Ziehl-Neelsenovo barvanje je razkrilo številne acidofilne bakterije. Imunohistokemično barvanje je pokazalo pozitivno imunobarvanje za Mycobacterium spp. To poročilo o primeru poudarja pomen upoštevanja zoonotskih tveganj pri mačkah z diagnozo primarne pljučne mikobakterioze. Ključne besede: mikobakterioza mačk; imunohistokemija; histopatologija; pluča