In an attempt to further understand the nature of atypical fibroxanthoma of the skin, 140 lesions were subjected to clinical, histologic, and histochemical studies. Atypical fibroxanthoma most commonly presented as a solitary, nonspecific nodule or ulceronodule on exposed skin of the face in the elderly. A clinical variant occurred in much younger persons on the covered areas of the trunk and limbs. Histologically, atypical fibroxanthoma develops as a circumscribed, cellular proliferation within the dermis, with occasional infiltration into the subcutis. Morphological patterns vary from lesions showing plump spindle cells in interlacing fascicles to those with haphazardly arranged large polyhedral cells. Bizarre multinucleated giant cells with foamy cytoplasm and numerous mitotic figures enhance its distrubing sarcoma‐like appearance. Among 101 patients followed for periods up to 15 years, no metastatic lesions were found and only nine lesions recurred. Correlation of the clinical and follow‐up data support the concept that in spite of its alarming histologic appearance, atypical fibroxanthoma of skin appears to behave in a benign manner.

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Clear cell basal cell carcinoma (BCC) is an unusual variant of BCC which is characterized by a variable component of large clear cells. Twenty cases are presented which are further subdivided into pure, mixed, or metatypical categories. Although initially thought to represent sebaceous or tricholemmal differentiation, electron microscopic studies demonstrated that the clear cell changes are a degenerative phenomenon, probably involving lysosomes.

Sclerema neonatorum and subcutaneous fat necrosis are rare disorders affecting the panniculus of the newborn. This review attempts to put into perspective their similarities and differences in light of historical, biochemical, pathologic, and etiologic considerations. Recent therapeutic modalities and the prognosis are discussed.