Multiple sclerosing pneumocytomas: a review.

Sclerosing pneumocytoma (SP) is a rare benign low-grade tumour of the lung, and typically presents as single discrete coin lesions on imaging. Multiple SP is an exceedingly rare entity and thus reported sparingly. We review the literature on multiple SP, their clinical presentations, histopathology, relevant differential diagnoses and molecular histogenesis of this entity. SP has a predilection for East Asian origin females who have never smoked. Patients are either asymptomatic or have symptoms such as cough, haemoptysis that may be persistent, chest pain if involving the pleura and presents as discrete coin lesion on chest X-ray. Histologically, they are papillary, solid, angiomatoid or sclerotic, or combinations of these four basic patterns. Multiple lesions have the same or slightly different histological patterns. They can be distributed in either lung, in any lobe and can even be bilateral. AKT-1 molecular pathways are pivotal in their molecular pathogenesis. In this review, we further propose a classification based on five types of distribution of multiple SP.

Expression patterns of markers for type II pneumocytes in pulmonary sclerosing hemangiomas and fetal lung tissues.

CONTEXT: Although the histogenesis of sclerosing hemangioma is currently not well understood, the tumor has been characterized by its 2 histologically different types of cells, namely, surface and polygonal cells. OBJECTIVE: To elucidate the origin of these cells, we analyzed samples from 15 cases of sclerosing hemangioma and 15 specimens of fetal lung tissue. DESIGN: We immunostained specimens from 15 cases of sclerosing hemangioma and 15 samples of fetal lung tissue using antibodies against thyroid transcription factor 1, MUC1, Thomsen-Friedenreich antigen, and CD44v6, known as markers for type II pneumocytes, and a panel of antibodies against cytokeratin, epithelial membrane antigen, synaptophysin, CD56, estrogen receptor, and progesterone receptor. RESULTS: In fetal lung tissue, MUC1 and thyroid transcription factor 1 were expressed throughout all developmental stages of airway epithelium, whereas Thomsen-Friedenreich antigen and CD44v6 were expressed by type II pneumocytes of saccular and alveolar origin. Thomsen-Friedenreich antigen was expressed in the bronchial bud of the pseudoglandular stage. MUC1, thyroid transcription factor 1, and epithelial membrane antigen were observed in both surface and polygonal cells of sclerosing hemangioma. Only the surface cells in all cases of sclerosing hemangioma showed positivity for cytokeratin and CD44v6. Thomsen-Friedenreich antigen was expressed in the surface cells of 11 of 15 cases of sclerosing hemangioma. Epithelial membrane antigen was expressed in both types of tumor cells, whereas cytokeratin was not detected on polygonal cells, but was reactive with surface cells. CONCLUSIONS: Our results suggest that the 2 types of cells in sclerosing hemangioma may derive from a common precursor cell through divergent differentiation toward the type II pneumocyte during tumorigenesis.

["Pneumocytoma" or "sclerosing hemangioma": histogenetic aspects of a rare tumor of the lung]. / "Pneumozytom" oder "sklerosierendes Hämangiom". Histogenetische Aspekte zu einem seltenen Lungentumor.

Aspects of histogenesis and nomenclature of so called "sclerosing hemangioma" of the lung (WHO 1999) are discussed and compared with immunohistochemical findings in eight examined operation specimen. The lesion is characterised by the presence of typical surface cells, which can be related to type II pneumocytes. Progesterone-receptor positive stromal cells may derive from primitive mesenchymal cells. Endothelial proveniance of tumor cells could not be confirmed by immunohistochemistry. Therefore, this rare usually benign pulmonary neoplasm should be entitled "pneumocytoma" analogous to the suggestion of several other authors.