Primary Pulmonary Perivascular Epithelioid Cell Tumour (PEComa): A Case Report.

Perivascular epithelioid cell tumour (PEComa) is a rare mesenchymal neoplasm; lung is an exceptional primary site. Herein, we present a surgically resected case of primary pulmonary PEComa and discuss its clinicopathologic features in comparison with previously published cases. A 47-year-old woman presented with a screening-detected right lower lobe nodule. Computed tomography showed a 26-mm S6 lesion abutting the A6. The patient underwent right S6 segmentectomy for diagnosis and treatment. The 30-mm mass was well demarcated and pearly white; histology showed epithelioid cells with sinusoid-like vasculature, rare mitoses and no necrosis. HMB45/Melan-A was positive for focal smooth muscle actin, confirming the diagnosis of PEComa. The patient remained disease free for > 1 year under observation without adjuvant therapy. Although primary pulmonary PEComa is rare and typically indolent, reports of malignant behaviour justify vigilant long-term surveillance and further case accumulation is warranted to refine the diagnostic criteria and management strategies.