Skin, Smooth muscle hamartoma

Smooth muscle hamartoma is a benign cutaneous tumor that is often found on the skin of the trunk and extremities. Most lesions are the congenital form, however, there have been reports of acquired lesions.

Histologically, proliferated smooth muscle cells organized in bundles are present in the papillary and reticular dermis. Although not seen in this case, there can be associated acanthosis and basal hyperpigmentation. Immunohistochemical stains such as smooth muscle actin and desmin can be performed to confirm the presence of smooth muscle proliferation. There is no risk of malignant transformation associated with this condition.