Progressive nodular histiocytoma.

Progressive nodular histiocytoma is a clinically distinct variant in the general group of normolipemic histiocytic proliferations. Its cardinal feature is the presence of two different lesions--a superficial yellow-brown papule and a deep nodule. We describe herein a 29-year-old man with such lesions. Histologically, a variety of fibrous and cellular patterns were seen, mimicking the wide spectrum of findings in ordinary dermatofibromas. On ultrastructural examination, the most striking feature of the preponderant cell was lipid phagocytosis.