Subcutaneous granuloma annulare and IgA-IgG2 deficiency.

Subcutaneous granuloma annulare (SGA) is a benign granulomatous disease occurring in childhood, with lesions most commonly located about the elbow, knee and scalp. the etiology of SGA remains obscure. We present a typical case with SGA also showing laboratory findings of IgA and IgG2 deficiency. Histologic findings of the lesions on the scalp were characterized by multiple large foci of complete collagen degeneration with a peripheral pallsade of histiocytes; the foci of degeneration was edematous basophilic. In contrast to current literature, an abnormality in the cellular immune system was not found. However, immune defects (IgA and IgG2 deficiency) related to the humoral immune system were observed.