Giant calcifying epithelioma

Calcifying epithelioma of Malherbe, or benign pilomatrixoma, is described as a skin tumor histologically composed of (1) "shadow" cells, (2) basophilic cells, (3) foreign body cells, and (4) intracellular and stromal calcifications. The dermatologic literature describes this tumor as a small benign lesion that never exhibits a malignant propensity. However, the recent surgical literature associates its enlarged size with its occasional aggressive behavior. In this regard, tumor dimension appears to influence prognosis. The term "giant calcifying epithelioma" appears taxonomically justified as a clinical description of this malignant tumor possessing histologic similarity to benign pilomatrixoma. The surgical literature has not previously stressed the mixed histologic characteristics of this pathologic variant. We report a case that demonstrates the malignant potential of giant calcifying epithelioma. The clinician should be alerted against a false security provided by the benign appearance of preoperative histologic sampling.