Solitary Cavitary Right Upper Lobe Lesion Revealing Disseminated Cryptococcosis in a Kidney Transplant Recipient: A Diagnostic Challenge.

Pulmonary cryptococcosis is an opportunistic fungal infection that primarily affects immunocompromised individuals, including solid organ transplant recipients. Its radiologic manifestations are diverse and may closely mimic malignancy or other chronic pulmonary infections, often leading to diagnostic uncertainty. We report a case of disseminated cryptococcosis presenting as a solitary cavitary pulmonary lesion in a kidney transplant recipient receiving chronic immunosuppressive therapy. Imaging findings initially raised concern for malignancy. Cytologic evaluation demonstrated fungal elements favoring Histoplasma, complicating the diagnostic process. However, microbiologic cultures and cryptococcal antigen testing confirmed Cryptococcus neoformans. Cerebrospinal fluid analysis demonstrated central nervous system involvement. The patient was treated with induction antifungal therapy followed by consolidation and maintenance therapy, with clinical and radiographic improvement. This case highlights the diagnostic challenges of pulmonary cryptococcosis and underscores the importance of integrating imaging, pathology, microbiology, and antigen testing to establish the diagnosis in immunocompromised patients.