Cystic fibrohistiocytic tumours presenting in the lung: primary or metastatic disease?

Cystic fibrohistiocytic tumour of the lung is a rare proliferative process. Its histogenesis is uncertain, but evidence suggests that some cases represent metastatic disease from apparently indolent skin lesions, namely cellular fibrous histiocytomas. This study presents four cases and reviews the literature concerning this pattern of disease and its aetiology.

All patients were male (age range 35-54 years). Two presented with recurrent haemoptysis. Two cases had histories of cutaneous fibrohistiocytic lesions in the chest wall, excised 10 and 23 years prior to presentation with lung disease. Imaging data showed multiple bilateral cystic lung lesions in all four patients with nodular cavitating opacities seen on high-resolution computed tomography scans. Microscopy showed variably dilated thin-walled cystic airspaces lined by cuboidal epithelium and an underlying layer of mildly pleomorphic spindle cells with slightly wavy morphology and storiform architecture, admixed with inflammatory cells. Tumour cells stained for CD68 in three of four cases. All cases were negative for CD34. All patients were alive with disease, although one required pneumonectomy for intractable haemoptysis.

This study and a review of published cases show that the majority of cystic fibrohistiocytic tumours of the lung probably represent metastases from cellular fibrous histiocytomas. However, rare cases may be either primary in origin or the primary site remains occult; the term cystic fibrohistiocytic tumour remains appropriate for such cases.