Indeterminate cell histiocytosis

Indeterminate cell histiocytosis (LCH) is an uncommon proliferative illness where the predominant cells have characteristics from both non-Langerhans cell histiocytosis (NLCH) and Langerhans cell histiocytosis (LCH) in terms of morphology and immunophenotypic characteristics. Wood et al. originally described ICH in 1985 as a neoplastic disease arising from dermal indeterminate cells that lack Birbeck granules but are characteristically positive for S-100 and CD1a.

Signs and symptoms
Clinically, ICH is defined by pink to reddish, varying-sized, painless, non-itching papules or nodules that develop on otherwise healthy skin (sparing mucosae). These lesions can appear as a single, distinct group of lesions, or several generalized papules dispersed over the trunk, face, and limbs. They can also show signs of stable disease, remission and recurrence, or spontaneous remission.

Causes
Possible causes include scabies, mosquito bites, and a clonal drive.

Treatment
Treatment include 5% 5-fluorouracil cream, topical pure coal tar, electron beam therapy, phototherapy, and total excision.