A morphological and immunohistochemical study of 25 cases of so-called sclerosing haemangioma of the lung.

The so-called sclerosing haemangioma of the lung is an uncommon tumour with predilection for Chinese women. Twenty-five cases showed a predominantly solid/cellular pattern in three, a haemorrhagic/angiomatoid pattern in three, a papillary pattern in one, a sclerotic pattern in one, and in seventeen, a mixed pattern was observed. Immunostaining revealed the expression of epithelial membrane antigen, vimentin (V9), and CD68 (KP1) in all tumours, cytokeratin in 23 (Cam 5.2 and MNF116), S-100 protein in 22 and alpha-smooth muscle actin in 23 tumours. All tumours were negative for surfactant, factor VIII-related antigen, CD34 and MAC387. There was strong labelling for progesterone receptor protein in 20 tumours, and oestrogen receptor protein was weakly stainable in 13 tumours. The histogenesis of sclerosing haemangioma of the lung is controversial and origin from pneumocyte, histiocyte, mesothelial, endothelial and Clara cell has been suggested. Our immunohistochemical findings, in the largest series studied to date, indicated a cytokeratin+, vimentin+, epithelial membrane antigen+, alpha-smooth muscle actin+, CD68+, oestrogen+, progesterone+ phenotype, confirming an epithelial lineage but which does not clearly correspond to any recognized cell in the respiratory system. The distinct expression of progesterone and oestrogen receptor proteins correlates with the predilection of this tumour for women.