Coinfection by Paracoccidioidomycosis and Cryptococcosis Mimicking Pulmonary Metastases in an Oncology Patient: Case Report

Pulmonary nodules are common findings in imaging exams and may suggest various diagnoses, such as infections and malignant neoplasms, often with indistinguishable radiological characteristics. A 75-year-old male rural worker, previously diagnosed with colorectal cancer, presented multiple bilateral pulmonary nodular lesions on computed tomography (CT) during follow-up after surgery and chemotherapy, suggestive of metastases. An initial decision was made for clinical and radiological follow-up. After three years of follow-up without significant changes in the images, lobectomy was performed during the same surgical procedure as intestinal tract reconstruction, and tissue was sent for histopathological examination. Histopathology revealed fibrotic granulomas with polymorphic yeasts and no evidence of malignancy. Histochemical and morphological features indicated concomitant infection by Cryptococcus sp. and Paracoccidioides brasiliensis, establishing the diagnosis of simultaneous cryptococcosis and paracoccidioidomycosis. The presence of pulmonary nodules in cancer patients often raises suspicion of secondary malignancy. Pulmonary infections and neoplasms, although distinct entities, may share similar clinical manifestations and radiological findings, complicating differential diagnosis. Oncologic patients, due to their immunocompromised status, are more susceptible to fungal infections, and coinfections by different fungi have been previously reported. The clinical picture is often nonspecific, including cough, dyspnea, hemoptysis and fever. On CT, fungal infections may present as solid nodules with irregular or spiculated margins, cavitated masses or consolidations, mimicking neoplasms. Studies show that up to 1.3% of pulmonary nodules later diagnosed as fungal infections are initially considered metastases. This similarity may delay appropriate treatment and lead to unnecessary interventions. Thus, in cancer patients with pulmonary nodular findings, it is essential to consider fungal infections in the differential diagnosis.