A case report on incidentally detected pulmonary sclerosing pneumocytoma: a diagnostic challenge.

Introduction and importance: Pulmonary sclerosing pneumocytoma (PSP) is a rare non-cancerous lung tumor that is usually asymptomatic, but may cause respiratory distress if it becomes large. PSPs are often detected incidentally because of their slow growth, lack of symptoms, characteristic radiographic features, and increased use of imaging studies. Although it is not a malignant tumor, it can mimic malignancy on imaging and histology, leading to misdiagnosis and unnecessary surgery. Case presentation: A 23-year-old asymptomatic female was incidentally diagnosed with PSP during evaluation for a breast fibroadenoma. A chest CT revealed a 3 cm lobulated mass in the left upper lobe. Cytology showed malignant cells with necrotic debris. Immunohistochemistry was positive for TTF-1 and EMA, negative for p63 and AE1/AE3. Histopathology confirmed a well-circumscribed benign neoplasm, consistent with pulmonary sclerosing pneumocytoma. There was no mediastinal lymph node invasion, and the post-surgery prognosis was good. Clinical discussion: PSP is a slow-growing tumor that is often asymptomatic until it reaches a significant size. Owing to their well-circumscribed margins and the presence of calcifications, they are often detected incidentally during imaging studies, such as routine chest radiography or CT scans for unrelated conditions. Although these tumors are often incidental, it is important to diagnose and treat them appropriately to prevent potential complications and malignant transformation. Conclusion: The findings of this study contribute to the existing literature, increase awareness of this rare tumor, and provide insights into its diagnosis, treatment, and follow-up.