Sclerosing haemangioma of the lung is positive for MIB-1 in cell membrane and cytoplasmic staining pattern

AIMS: MIB-1 is a monoclonal antibody raised against the recombinant part of the Ki67 antigen, which is expressed in the nuclei of all the active part of the cell cycle. Recently, cell membrane and cytoplasmic pattern of staining with MIB-1 in hyalinizing trabecular adenoma of the thyroid was reported. Sclerosing haemangioma of the lung is a tumour of uncertain histogenesis with a usually benign course. The tumour is mainly composed of cuboidal cells that line the papillary or tubular structure and pale cells that are found in the stroma. METHODS AND RESULTS: We examined a cell membrane and cytoplasmic immunoreactive pattern for MIB-1 antibody in sclerosing haemangioma. In all of the five cases examined, distinct cell membrane and cytoplasmic MIB-1 positivity mainly in the pale cells was noted. None of the carcinomas of the lung showed this type of staining with MIB-1. CONCLUSION: This result shows that, although the staining may be a result of cross reaction, cell membrane and cytoplasmic MIB-1 positivity is unique in that it could distinguish sclerosing haemangioma from other malignant epithelial tumours of the lung.