Linear and Bilateral Multinucleated Cell Angiohistiocytoma (MCAH).

Background: Multinucleated Cell Angiohistiocytoma (MCAH) is a rare disease, first described by Smith and Wilson Jones in 1985. Since then, less than 100 cases have been reported in the literature. Clinically it is characterized by papules or plaques arising from a specific anatomical area such as lower extremities, dorsum of the hands and face. Some generalized cases have been reported.

Main observations: We report a case of 77-year-old woman who presented with multiple itching. reddish to violaceous, flat to domed-shaped plaques on the lower legs with symmetrical and bilateral distribution along the saphena veins. On dermoscopy examination only a red-violaceous homogeneous area was visible. Histology showed remarkable proliferation of dilated small vessels in the upper and mid dermis and bizarre-shaped multinucleate giant cells with scalloped cytoplasm that were intermingled with numerous mononucleated spindle cells. Many mast cells containing the characteristic granules were also detected, often adjacent to the multinucleate cells. Based on the clinico-pathologic findings the diagnosis of MCAH was established.

Conclusions: To our knowledge, this is the first documented case of MCAH with a bilateral and linear pattern disposed on the lower limbs, following the saphena veins. In this patient chronic trauma induced by ambulation might have contributed to development of the lesions.