BACKGROUNDTo study the morphological characteristics, immunohistochemical stain and histological origin of so-called sclerosing hemangioma of the lung (S-SH), and to investigate the significance and diagnostic value of expressions of surfactant protein B (SP-B), thyroid transcription factor-1 (TTF-1) and other markers in S-SH.

METHODSUsing transmission electron microscope and immunohistochemistry methods, the expressions of SP-B, TTF-1, mast cell trypsin (MCT), epithelial antigen markers (CK-H, CK-L, EMA, CEA), mesothelial antigen (MC), neuroendocrine markers (NSE, Ch-A, synaptophysin, calcitonin, ACTH, GH), vimentin and CD34 were observed in 30 cases of S-SH.

RESULTSS-SH demonstrated a mixture of four histological patterns: solid, papillary, hemorrhagic and sclerotic pattern, which often showed transitional phenomena. Cuboidal cells on the surface, which contained short microvilli and lamellar bodies in cytoplasm, arranged in one row and sometimes interfused into multinuclear giant cells. Immunohistochemical results showed that these cells demonstrated strongly positive staining to SP-B, TTF-1, CK-L, EMA and CEA. The other major cell component-polygonal stromal cells were strongly positive to vimentin and TTF-1, and positive or weakly positive to 2 or 3 neuroendocrine markers in each case. Sparse neuroendocrine granulae and abundant microtubules were observed in cytoplasm of the cells. Both cuboidal and polygonal cells displayed negative immunohistochemical results to CD34 and MC. Some cell clusters in solid region were positive for SP-B and EMA. Mast cells which were positive for MCT existed sparsely in almost full vision field.

CONCLUSIONSCuboidal cells of S-SH originate from reactive proliferating type II pneumocytes and sometimes interfuse into multinuclear giant cells. The polygonal cells in stroma probably originate from multipotential primitive respiratory epithelium and have multiple differentiating ability. The presence of mast cells is also one of histological characteristics of S-SH.