Dermatofibroma with Monster Cells

A 72 year old man was seen with a four month history of a tumor on the left calf.

He is a light complected Caucasian with Type II skin.  The lesion is solitary, 9 mm in diameter.  It had a peculiar reddish brown color.

Clinical Photo:

Dermatoscopic Image

The lesion was excised.

Pathology:
Shows that this is a cellular dermatofibroma with monster cells.
Photomicrographs courtesy of Dr. Jag Bhawan.

4x

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Diagnosis:  Dermatofibroma with Monster Cells.  There are only four citations in PubMed on monster cells in dermatofibroma, and none of these is available fre online.  Thus, there are no accessible clinical or histopathological images online.  This post may be of interest to our readers.

Reference:
Dermatofibroma with monster cells.

Tamada S, Ackerman AB.  Am J Dermatopathol. 1987 Oct;9(5):380-7.

Abstract: Nineteen cases of dermatofibroma associated with monster cells are reported. The term "monster" (an animal with a strange or terrifying shape, one unusually large for its kind) implies a strikingly atypical cell with an extremely large nucleus. Except for monster cells, these 19 lesions had all of the typical histopathological findings of dermatofibroma. The clinical diagnosis for 16 of these lesions was dermatofibroma (or histiocytoma). Three lesions were submitted without any clinical diagnosis. Eighteen of 19 lesions occurred on the extremities. One was on the back. Monster cells are seen in the early, histiocytic stage of dermatofibroma when lipophages and/or siderophages are usually present in large numbers. Only rarely were mitotic figures seen in dermatofibromas with monster cells, and they were neither numerous nor atypical. It is important for histopathologists to distinguish dermatofibroma with monster cells from cutaneous malignant fibrous histiocytoma and radiation sarcoma. The criteria for differentiation concern primarily the architectural pattern of the lesion rather than its cytological features.