Cutaneous mixed tumor with lipomatous stroma.

AIM

Mixed tumors are usually composed of two components, one epithelial and the other mesenchymal. The latter component is commonly myxoid or myxochondroid; a massively lipomatous stroma is very unusual. To date, only two cases of mixed tumor of the skin have been reported with this type of stroma.

METHODS AND RESULTS

We report the case of a 61-year-old man with a mixed tumor situated on the hand, an unusual site for these tumors, with over 90% of the tumor composed of adipose tissue. The tumor was a well-circumscribed, 4.5-cm mass, with the gross appearance of a lipoma. The lipomatous stroma contained nests and ribbons of epithelial cells, with occasional tubular structures, surrounded by a scarce amount of fibromyxoid tissue. Immunohistochemical study showed findings similar to those seen in classic mixed tumors.

CONCLUSION

Together with a few other cases in the skin and parotid gland, this report shows how massive adipose differentiation can arise in a mixed tumor of the skin.