Purely cutaneous sclerosing IgG4-related disease of the cephalic region: case report and a mini-review of the clinical and pathological aspects.

IgG4-related disease is a recently defined emerging entity. Many different organs may be affected by this disease: pancreas, salivary and lacrimal glands, liver, peritoneum and lung. Also the skin may be affected, as secondary localization, while as primary cutaneous localization it has been rarely described. A male patient presented at our Institute with a two-year history of sclerosing erythematous nodules of the scalp. Histological examination showed a T-lymphocyte (CD3+) infiltrate with interspersed plasmacytoid cells and the interposition of a fibrosclerotic tissue. We found numerous IgG4+ cells at the periphery of the nodular structures, while the serum levels of IgG4 and the remaining blood chemistry analysis were normal. Only a few cases of primitive cutaneous pseudo-lymphomatous IgG4-related disease have been described in the literature. Our case showed the same clinical and histologic features of those previously described; the etiology of IgG4-related diseases remains to be elucidated.