Xuan Wang1, Cynthia M Magro. 1. Department of Pathology and Laboratory Medicine, Room F-309, 1300 York Avenue, Weill Medical College of Cornell University, New York 10065, United States of America.
Abstract
BACKGROUND: Substantial clinicohistologic overlap exists between lupus erythematosus profundus (LEP) and lymphomas involving the subcutis, including subcutaneous panniculitis-like T-cell lymphoma (SPTCL) and primary cutaneous gamma/delta T-cell lymphoma (GDTCL). Unequivocal markers separating the entities are not established. OBJECTIVES: To explore the usefulness of interferon alpha (INF-α)-induced protein, myxovirus resistance protein 1 (MxA), in the differential diagnosis of these entities, as studies show that the expression pattern of MxA follows the distribution of the inflammatory infiltrate in cutaneous lupus, while INF- α is not known to operate in lymphoma. MATERIALS AND METHODS: MxA immunohistochemistry was performed on skin biopsies from 5 patients with a clinical and histological diagnosis of SPTCL, 9 patients with GDTCL and 9 patients with LEP. RESULTS: In SPTCL and GDTCL, MxA was primarily seen in macrophages and generally did not exceed 20% of the infiltrate. In contrast, a significant portion of the subcutaneous infiltrate was positive for MxA in LEP, with 50% of the infiltrate staining on average. A greater number of macrophages and lymphocytes stained with a greater intensity as well (P<0.001). Moreover, endothelial cell staining was uniquely identified in LEP but not in lymphoma. CONCLUSION: Although specificity is not 100%, minimal staining of MxA is a predictor for SPTCL or GDTCL. Conversely, extensive staining for MxA both qualitatively and quantitatively is a feature of LEP. Endothelial staining also appears to be specific for LEP.
BACKGROUND: Substantial clinicohistologic overlap exists between lupus erythematosus profundus (LEP) and lymphomas involving the subcutis, including subcutaneous panniculitis-like T-cell lymphoma (SPTCL) and primary cutaneous gamma/delta T-cell lymphoma (GDTCL). Unequivocal markers separating the entities are not established. OBJECTIVES: To explore the usefulness of interferon alpha (INF-α)-induced protein, myxovirus resistance protein 1 (MxA), in the differential diagnosis of these entities, as studies show that the expression pattern of MxA follows the distribution of the inflammatory infiltrate in cutaneous lupus, while INF- α is not known to operate in lymphoma. MATERIALS AND METHODS:MxA immunohistochemistry was performed on skin biopsies from 5 patients with a clinical and histological diagnosis of SPTCL, 9 patients with GDTCL and 9 patients with LEP. RESULTS: In SPTCL and GDTCL, MxA was primarily seen in macrophages and generally did not exceed 20% of the infiltrate. In contrast, a significant portion of the subcutaneous infiltrate was positive for MxA in LEP, with 50% of the infiltrate staining on average. A greater number of macrophages and lymphocytes stained with a greater intensity as well (P<0.001). Moreover, endothelial cell staining was uniquely identified in LEP but not in lymphoma. CONCLUSION: Although specificity is not 100%, minimal staining of MxA is a predictor for SPTCL or GDTCL. Conversely, extensive staining for MxA both qualitatively and quantitatively is a feature of LEP. Endothelial staining also appears to be specific for LEP.