title: Claudin-1 is expressed in perineurioma-like low-grade fibromyxoid sarcoma.
abstract: Low-grade fibromyxoid sarcoma is a soft tissue sarcoma with recurrent and low metastatic potential, which has characteristic FUS-CREB3L2 or FUS-CREB3L1 fusions. Perineurioma is a peripheral nerve sheath neoplasm, which is usually benign. Low-grade fibromyxoid sarcoma and perineurioma can appear morphologically similar, particularly in small biopsy specimens, and distinction between the 2 entities is important for appropriate treatment. Low-grade fibromyxoid sarcoma is negative for most immunohistochemical markers, whereas perineuriomas stain variably for epithelial membrane antigen, CD34 and claudin-1, a tight-junction associated protein. We studied 15 cases of genetically proven low-grade fibromyxoid sarcoma that at least focally resembled perineurioma, with antibodies to claudin-1 and epithelial membrane antigen. Of these, 11 showed positivity for epithelial membrane antigen and all 15 were positive for claudin-1; in all cases, expression of claudin-1 was equal to or greater than the corresponding epithelial membrane antigen expression. This study emphasizes that claudin-1 is significantly expressed in low-grade fibromyxoid sarcomas. This has implications toward the accurate diagnosis of both tumors, and, as positivity for claudin-1 in low-grade fibromyxoid sarcoma is not previously documented, suggests that there might be underdiagnosis of low-grade fibromyxoid sarcoma. Although positivity for claudin-1 remains useful as an adjunct marker for perineurioma, it should be taken in context with clinical findings, morphology, and the additional immunoprofile.
authors.affiliation: Department of Histopathology, Royal Marsden Hospital, London SW3 6JJ, UK. khin.thway@rmh.nhs.uk
authors.forename: Khin
authors.initials: K
authors.lastname: Thway
authors.forename: Cyril
authors.initials: C
authors.lastname: Fisher
authors.forename: Maria
authors.initials: M
authors.lastname: Debiec-Rychter
authors.forename: Eduardo
authors.initials: E
authors.lastname: Calonje
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000032:analysis*; D002648:Child; D062445:Claudin-1; D003937:Diagnosis, Differential; D005260:Female; D005354:Fibrosarcoma / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D008565:Membrane Proteins / Q000096:biosynthesis*; D008875:Middle Aged; D018396:Mucin-1 / Q000096:biosynthesis; D018317:Nerve Sheath Neoplasms / Q000378:metabolism / Q000473:pathology*; D012983:Soft Tissue Neoplasms / Q000378:metabolism / Q000473:pathology*; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor; C568108:CLDN1 protein, human; D062445:Claudin-1; D008565:Membrane Proteins; D018396:Mucin-1