The patient, a 39-year-old female, was admitted on 14-Nov-2023 with "cough for 2 months". At the time of admission, there were no obvious abnormalities in the specialist physical examination, and the nucleic acid tests of tumor markers and common respiratory pathogens were negative. Chest plain scan + enhanced CT showed a round-like nodular shadow in the upper lobe of the left lung, with clear boundary, about 27 mm ×21 mm in size, and adjacent vascular signs around it. The enhanced scan showed a relatively uniform moderate enhancement (CT value 64~80 HU), and punctate calcification was visible (arrows in Figures 1 and 2). Thoracoscopic partial resection of the upper lobe of the left lung was performed to confirm the diagnosis. Pathology showed a benign tumor in the upper lobe of the left lung, which was a mixture of solid, papillary, sclerosing and angiomatous tissue structures (FIG. 3, hematoxylin-eosin staining ×100). Immunohistochemistry showed that the expression of thyroid transcription factor (TTF-1) was positive in alveolar epithelial cells and interstitial cells, vimentin interstitial cells of tumor cells and cytokeratin alveolar epithelium; The expression of smooth muscle actin, anaplastic lymphoma kinase and desmin were negative. Sclerosing alveolar cell tumor (PSP) was diagnosed. PSP is a rare benign lung tumor in clinic, which is more common in women. The incidence rate accounts for about 0.2% ~1.0% of primary lung tumors. It grows slowly, has less metastasis, and has a good prognosis. Complete surgical resection is the first choice of treatment. PSP includes surface cubic epithelial cells and mesenchymal circular cells, and its internal components mainly include papillary area, solid area, sclerosis area and hemangioma-like area. PSP consists of at least 2 or more (mostly 3 or more) ingredients. Typical CT images show round or quasi-round nodules, and larger ones can show solitary masses, with most lesions with clear boundaries and may be accompanied by calcifications; It may also be manifested as enhancement, the degree and manner of enhancement depending on tissue composition and lesion size. Small lesions were mainly hemangioma-like and papillary areas, with dense vascular distribution and obvious and uniform early enhancement; With the enlargement of the lesion, the proportion of solid and sclerotic areas increased, and the distribution was uneven, the vascular distribution was sparse, and the degree of enhancement was low. The special signs were welt vascular sign and halo sign.
