title: Alpha-inhibin immunoreactivity in soft-tissue neoplasia.
abstract: Antibodies directed against alpha-inhibin have been previously reported as staining both sex cord-stromal neoplasms as well as adrenal cortical tumors. This relatively restricted immunoreactivity pattern is useful in the assessment of retroperitoneal masses, especially in a setting of limited tissue (e.g., needle biopsy). However, no study to date has evaluated alpha-inhibin immunoreactivity in soft-tissue neoplasms, which frequently enter the differential diagnosis of retroperitoneal masses. We investigate the incidence of alpha-inhibin staining in a variety of soft-tissue neoplasms by using formalin-fixed, paraffin-embedded tissue sections from 282 previously classified soft-tissue neoplasms with anti-alpha-inhibin (Serotec, 1:75). A modified avidin-biotin complex method was used after heat-induced epitope retrieval. Cytoplasmic granular staining was considered positive. Of the 282 tumors studied, a total of 8 (2.8%) demonstrated positive staining with anti-alpha-inhibin antibody. These included 4 of 25 liposarcomas (16%), 2 of 18 angiosarcomas (11%), 1 of 48 lipomas (2.1%), and 1 of 1 rhabdomyoma (100%). Negative staining was noted among hemangiomas (0/28), schwannomas (0/32), leiomyomas (0/16), fibrosarcomas (0/2), fibromas (0/11), dermatofibromas (0/9), neurofibromas (0/6), synovial sarcomas (0/15), rhabdomyosarcomas (0/10), Triton tumors (0/2), and malignant fibrous histiocytomas (0/59). We conclude that rare soft-tissue tumors, especially those exhibiting either lipomatous or vascular differentiation, demonstrate alpha-inhibin immunoreactivity. These findings re-emphasize the need for a well-construed antibody panel when immunohistochemical methods are employed in the evaluation of retroperitoneal neoplasms. However, the rarity of alpha-inhibin expression by soft-tissue neoplasms provides further support for its overall specificity as a marker of adrenal cortical differentiation in the biopsy evaluation of a retroperitoneal mass.
authors.affiliation: Department of Pathology, University of Iowa Hospitals and Clinics, Iowa City, Iowa 52242, USA.
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Schraith
authors.forename: Geoffrey K
authors.initials: GK
authors.lastname: Hahm
authors.forename: Theodore H
authors.initials: TH
authors.lastname: Niemann
authors.forename: Barry R
authors.initials: BR
authors.lastname: DeYoung
mesh_terms: D006801:Humans; D007150:Immunohistochemistry; D007265:Inhibins / Q000032:analysis*; D018204:Neoplasms, Connective and Soft Tissue / Q000378:metabolism / Q000473:pathology*
chemical_list: C094377:inhibin-alpha subunit; D007265:Inhibins