Sclerosing haemangioma of the lung. A histochemical, electron microscopical, tissue culture and time‐lapse cinematographic study

A case of pulmonary sclerosing haemangioma was studied by electron microscopy, tissue culture, time-lapse cinematography and enzyme histochemistry. The cells bordering the spaces and forming solid sheets showed abundant surface microvilli, desmosomes and osmiophilic inclusions some of which had a lamellar structure. No Weibel-Palade bodies were found. The cells showed a negative reaction to ATP-ase and stained focally for alkaline phosphatase. Normal cells inside the tumour showed positive reactions for both enzymes. In tissue culture, both conventional studies and time-lapse cinematography showed a rather characteristic behaviour unrelated to that previously described in other neoplasms or in cultures of normal lung. The findings contradict the view that pulmonary sclerosing haemangiomas are proliferations of immature respiratory epithelial cells.