Hyaline-vascular castleman disease: a rare cause of solitary subcutaneous soft tissue mass.

Castleman disease (CD) is a rare lymphoproliferative disorder that primarily affects mediastinal, retroperitoneal, and cervical lymph nodes. Clinically, these lesions occur as a localized (unicentric) or less frequently as a systemic (multicentric) disease. Two main distinct histologic variants are recognized, the more common hyaline-vascular (HV) type and the plasma cell (PC) type. Extranodal Castleman disease, HV type (HVCD) is even less common. We describe a case of subcutaneous HVCD in a 57-year-old woman with a palpable chest mass and without systemic symptoms. Although the histologic findings are similar to those of HVCD in lymph nodes and other sites, a plethora of differential diagnosis is raised particularly with the more commonly occurring lymphoproliferative lesions in this location. This is one of the few bona fide cases of HVCD in subcutaneous location published to date. A review of the literature with an emphasis on pathogenesis of the disease subtypes is presented.