Pigmented actinic keratosis is one of the simulators of early melanoma in situ from severely sun-damaged skin. Close scrutiny of the hematoxylin and eosin stained section does not always allow an unequivocal diagnosis...Pigmented actinic keratosis is one of the simulators of early melanoma in situ from severely sun-damaged skin. Close scrutiny of the hematoxylin and eosin stained section does not always allow an unequivocal diagnosis, because it is sometimes difficult to distinguish pigmented keratinocytes from melanocytes. Immunohistochemical stains, such as S-100 and HMB-45, are used routinely to address this problem. Melan-A, also known as MART-1, is an additional melanocytic marker and has proved to be useful in identifying metastatic tumors of melanocytic origin. The usefulness of this marker to discriminate pigmented actinic keratosis from early melanoma in situ, however, has not yet been a subject of investigation. In this study we evaluatedMelan-A expression in ten unequivocal cases of pigmented actinic keratosis and compared the staining pattern with that of S-100, HMB-45, and tyrosinase. In all ten cases the number of cells highlighted with Melan-A was by far larger than those labeled with S-100, HMB-45, and tyrosinase. Four cases showed clusters of Melan-A positive cells being suggestive of melanocytic nests. Even areas of normal skin adjacent to the actinic keratosis featured prominent staining of Melan-A, but only inconsistent labeling of intraepidermal melanocytes with S-100, HMB-45, and tyrosinase. We therefore believe that Melan-A is a more sensitive marker for intraepidermal melanocytes than S-100, HMB-45, and tyrosinase. In addition there may be expression of Melan-A in keratinocytes and nonmelanocytic cells. To avoid an erroneous diagnosis of malignant melanoma one should therefore interpret results ob-tained fromMelan-A stained slides carefully and in the context with other melanocytic markers.展开更多
Background: Inflammatory pseudotumor (IPT) also known as inflammatory myofibroblastic tumor (IMT) or plasma cell granuloma (PCG) has been rarely reported in the skin. Methods: We describe five patients with cutaneous ...Background: Inflammatory pseudotumor (IPT) also known as inflammatory myofibroblastic tumor (IMT) or plasma cell granuloma (PCG) has been rarely reported in the skin. Methods: We describe five patients with cutaneous IPT and present clinicopathologic features along with detailed immunohistochemical analysis including anaplastic lymphoma kinase (ALK)-1. Results: The patients age ranged from 15 to 89 years with a median of 56 years. All patients presented with solitary, firm, papules and nodules. There was no evidence of constitutional symptoms, local recurrence, or lymph node involvement. Histopathological examination revealed two distinct patterns; one type (n = 3) displayed dense, lymphoplasmacytoid infiltrates containing lymphoplasmacytoid cells and plasma cells with occasional germinal centers and hyalinized collagen bundles but was devoid of a myofibroblastic component. It showed features of tumors previously described as cutaneous PCG. Although an infectious etiology, including Borrelia burgdorferi-specific DNA, could not be demonstrated, we observed many features that overlapped with those of fibrous nodules of acrodermatitis chronica atrophicans. The other pattern (n = 2) revealed spindled myofibroblasts focally arranged in a fascicular pattern, an admixed lymphoplasmacytoid infiltrate set in a background of thickened collagen bundles, findings akin to the conventional type of EMT. The cases with a myofibroblastic component (n = 2) did not show any evidence of ALK-1 reactivity. Conclusions: We believe that the term cutaneous IPT subsumes lesions of diverse etiology. Tumors with detectable myofibroblasts represent true cases of IMT. Cutaneous PCG is a discrete disorder biologically distinct from conventional IMT representing a reaction pattern that is also found in disorders, such as spirochete-induced fibroid nodules and localized chronic fibrosing vasculitis.展开更多
文摘Pigmented actinic keratosis is one of the simulators of early melanoma in situ from severely sun-damaged skin. Close scrutiny of the hematoxylin and eosin stained section does not always allow an unequivocal diagnosis, because it is sometimes difficult to distinguish pigmented keratinocytes from melanocytes. Immunohistochemical stains, such as S-100 and HMB-45, are used routinely to address this problem. Melan-A, also known as MART-1, is an additional melanocytic marker and has proved to be useful in identifying metastatic tumors of melanocytic origin. The usefulness of this marker to discriminate pigmented actinic keratosis from early melanoma in situ, however, has not yet been a subject of investigation. In this study we evaluatedMelan-A expression in ten unequivocal cases of pigmented actinic keratosis and compared the staining pattern with that of S-100, HMB-45, and tyrosinase. In all ten cases the number of cells highlighted with Melan-A was by far larger than those labeled with S-100, HMB-45, and tyrosinase. Four cases showed clusters of Melan-A positive cells being suggestive of melanocytic nests. Even areas of normal skin adjacent to the actinic keratosis featured prominent staining of Melan-A, but only inconsistent labeling of intraepidermal melanocytes with S-100, HMB-45, and tyrosinase. We therefore believe that Melan-A is a more sensitive marker for intraepidermal melanocytes than S-100, HMB-45, and tyrosinase. In addition there may be expression of Melan-A in keratinocytes and nonmelanocytic cells. To avoid an erroneous diagnosis of malignant melanoma one should therefore interpret results ob-tained fromMelan-A stained slides carefully and in the context with other melanocytic markers.
文摘Background: Inflammatory pseudotumor (IPT) also known as inflammatory myofibroblastic tumor (IMT) or plasma cell granuloma (PCG) has been rarely reported in the skin. Methods: We describe five patients with cutaneous IPT and present clinicopathologic features along with detailed immunohistochemical analysis including anaplastic lymphoma kinase (ALK)-1. Results: The patients age ranged from 15 to 89 years with a median of 56 years. All patients presented with solitary, firm, papules and nodules. There was no evidence of constitutional symptoms, local recurrence, or lymph node involvement. Histopathological examination revealed two distinct patterns; one type (n = 3) displayed dense, lymphoplasmacytoid infiltrates containing lymphoplasmacytoid cells and plasma cells with occasional germinal centers and hyalinized collagen bundles but was devoid of a myofibroblastic component. It showed features of tumors previously described as cutaneous PCG. Although an infectious etiology, including Borrelia burgdorferi-specific DNA, could not be demonstrated, we observed many features that overlapped with those of fibrous nodules of acrodermatitis chronica atrophicans. The other pattern (n = 2) revealed spindled myofibroblasts focally arranged in a fascicular pattern, an admixed lymphoplasmacytoid infiltrate set in a background of thickened collagen bundles, findings akin to the conventional type of EMT. The cases with a myofibroblastic component (n = 2) did not show any evidence of ALK-1 reactivity. Conclusions: We believe that the term cutaneous IPT subsumes lesions of diverse etiology. Tumors with detectable myofibroblasts represent true cases of IMT. Cutaneous PCG is a discrete disorder biologically distinct from conventional IMT representing a reaction pattern that is also found in disorders, such as spirochete-induced fibroid nodules and localized chronic fibrosing vasculitis.
