Atypical Histiocyte-Rich Sweet's Syndrome

Abstract

Sweet's Syndrome is a rare neutrophilic dermatosis thought to be a result of immune dysregulation occurring in the setting of drug exposure, recent infection, pregnancy, and underlying malignancy or idiopathic with specific and widely accepted diagnostic criteria established in the literature. Other organ systems can be involved with varying degrees of severity. An unusual case of Sweet's Syndrome associated with myopericarditis, acral involvement, and atypical histological findings with predominance of histiocytes is described here.

Figure 1

Skin findings. (a) Edematous papules and plaques of acute lesions of Sweet's Syndrome. (b) Well-established lesions of Sweet's Syndrome consisting of annual papules and plaques with scale and crust. (c) Finger changes seen in our patient with subungual inflammation splinter hemorrhages and inflammation and scaling of several fingertips.

Figure 2

Biopsy findings. (a) Histological section showing fairly prominent papillary dermal edema and a somewhat dense dermal infiltrate comprised of mixed inflammatory cells (hematoxylin-eosin, original magnification: ×40). (b) Many large histiocytic cells are present as well as lymphocytes and scattered neutrophils (hematoxylin-eosin, original magnification: ×400). Leukocytoclastic debris is noted, but evidence of vasculitis is lacking. (c) Myeloperoxidase immunohistochemical stain reveals scattered neutrophils but is negative in the histiocytic cells (original magnification: ×200). (d) Histiocytic cells are confirmed to be histiocytes and not mononuclear myelocytes (CD163 immunohistochemical stain, original magnification: ×100). (e) Background T lymphocytes (CD3 immunohistochemical stain, original magnification: ×100).