Epidermal mast cells in Bowenoid papulosis during topical imiquimod therapy

Abstract

the plaque on the jaw and neck (Fig. 1c). Histological examination of the whitish lesion on the knee revealed deposition of homogeneously stained, cracked material surrounded by thick collagen fibers and fibroblasts within the papillary dermis, forming a pseudocyst structure (Fig. 1d). Calcification was confirmed by von Kossa staining (Fig. 1e). We diagnosed these lesions as milia-like idiopathic calcinosis cutis (MICC) in DS. The papule on the jaw showed multiple cystic ducts lined by cuboidal cells with comma-like tails in the dermis (Fig. 1f,g). We diagnosed this lesion as plaque-type syringoma. Down syndrome shows various cutaneous manifestations, such as atopic dermatitis, dry skin, elastosis perforans serpiginosa, alopecia areata, skin infections and syringoma. Syringoma is a benign eccrine sweat gland tumor, which usually appears as multiple tiny papules at the infraorbital area. Syringoma has been classified into four groups, according to their clinical features and associations: (i) localized form; (ii) generalized/eruptive form; (iii) a form associated with DS; and (iv) familial form. Plaque-type syringoma of localized form is rare, and was first described by Kikuchi et al. in 1979. Thereafter, only 12 cases of plaque-type syringoma have been reported, however, there has been no reports in a DS patient as in our case. Milia-like idiopathic calcinosis cutis is a whitish micronodular lesion, usually located on the hands and feet, without abnormality or alteration of the Ca-P metabolism. To the best of our knowledge, there have been 19 cases of MICC written in detail in the English-language published work including our case. Fifteen of 19 MICC cases (78.9%) were pediatric DS patients, and in 11 out of 15 MICC cases (73.3%) syringoma was present concurrently. It suggested that MICC may be closely related to or characteristic of pediatric DS patients. Additionally, only our case reported a DS patient who developed both plaque-type syringoma and MICC concurrently. Although the pathogenic mechanism of MICC and association with syringomas are unknown, several authors have suggested that an increase of the calcium content in the sweat leads to calcification of the acrosyringium. Schepis et al. reported a case in which calcium deposition was observed in syringoma in an 11-year-old girl with DS. However, we could not identify the deposition of calcium in the sweat glands in the biopsied tissues from jaw and knee lesions. In conclusion, we reported a very rare case of pediatric DS complicated with both MICC and plaque-type syringoma. Awareness of the complication of MICC and syringoma in pediatric DS patients is important for dermatologists to establish an accurate diagnosis.