Pulmonary Sclerosing Pneumocytoma: A Pre and Intraoperative Diagnostic Challenge. Report of Two Cases and Review of the Literature

Abstract

Pulmonary sclerosing pneumocytoma is a rare benign pulmonary tumor of primitive epithelial origin. Because of the unspecific radiological features mimicking malignancies and its histological heterogeneity, the differential diagnosis with adenocarcinoma and carcinoid tumors is still challenging. We report our experience of two cases of sclerosing pneumocytoma, as well as a review of the literature. Immunohistochemical findings showed intense staining of the cuboidal epithelial cells for cytokeratin-pool and TTF-1, with focal positivity for progesterone receptors. Round and spindle cells expressed positivity for vimentin, TTF-1 and focally for the progesterone receptor. Cytologic diagnosis of pulmonary pneumocytoma requires the identification of its dual cell population, made up of abundant stromal cells and fewer surface cells. Since the pre- and intraoperative diagnosis should guide surgical decision making, obtaining a sufficient specimen size to find representative material in the cell block is of paramount importance.

Central and peripheral pulmonary sclerosing pneumocytomas: multi-phase CT study and comparison with Ki-67

“…Overlying vessel sign is caused by the compressed blood vessels around the PSP lesions, reflecting the growing tendency of neighbor vessels to the tumors. 31 Previous studies showed that overlying vessel sign was more common in peripheral lesions. 30 , 31 However, similar to prominent pulmonary artery signs, the overlying vessel sign was more common in central PSPs in this study.…”

“… 31 Previous studies showed that overlying vessel sign was more common in peripheral lesions. 30 , 31 However, similar to prominent pulmonary artery signs, the overlying vessel sign was more common in central PSPs in this study. This may be due to the larger central PSPs being closer to the pulmonary hilar vascular branches.…”

Analysis of the value of enhanced CT combined with texture analysis in the differential diagnosis of pulmonary sclerosing pneumocytoma and atypical peripheral lung cancer: a feasibility study

“…PSP is composed of two basic types of tumour cells, namely, surface cells resembling type II pneumocytes and round cells; morphologically, PSP can be summarized into 4 characteristic areas (papillary area, solid area, sclerosis area, haemorrhage area), and the lesion is at least composed of two or more characteristic regions [ 13 ]. Pathological diagnosis of PSP before and during surgery is difficult, as some lesions need postoperative pathological examination and immunohistochemical analysis to make a definite diagnosis [ 9 , 14 ]. Maleki et al [ 8 ] believe that there is overlap between the morphological features of PSP and well-differentiated lung adenocarcinoma, so we should guard against the possibility of misdiagnosis.…”

“…At present, puncture biopsy and intraoperative rapid frozen pathology are important means to distinguish PSP from lung cancer. However, some studies have found it very challenging to distinguish PSP from lung cancer by needle biopsy or frozen section alone, and the misdiagnosis rate is quite high [ 7 – 9 ]. In addition, needle biopsy, as an invasive examination, carries the risk of bleeding, pneumothorax, and infection.…”

Pulmonary sclerosing pneumocytoma: A potential pitfall mimicking lung adenocarcinoma

“…In the present case report, also cytology report was suggestive of non-small cell carcinoma, as the cytological features were overlapping with that of lung adenocarcinoma. In any case, the cytologic heterogeneity of this tumor makes the diagnosis difficult because the smears can range from hypocellular, bloody, sclerotic to hypercellular, loaded with stromal fragments, and/or showing epithelial cell proliferation, depending on the needle biopsy sampling area (8).…”