Primary cutaneous signet ring cell carcinoma (PCSRCC) is a very unusual but distinctive clinicopathologic entity that can simulate metastatic adenocarcinomas. It is defined as a diffuse malignant epithelial neoplasia localized in the dermis and subcutis without epidermal involvement, showing variable amounts of signet ring cells, without evidence of visceral adenocarcinoma. We present 2 cases of PCSRCC, which involved eyelids and axilla respectively. Despite thorough systemic workup, primary sources could not be demonstrated in either case. The tumor cells are positive for gross cystic disease fluid protein 15 in addition to a variety of glandular markers. Furthermore, both cases were immunostained with cytokeratin 20 (CK20). In conclusion, we report 2 cases of PCSRCC expressing CK20 immunoreactivity. CK20-positive primary cutaneous tumors should include PCSRCC in addition to Merkel cell carcinoma.
We describe a case of CD34-positive infantile myofibromatosis with hemangiopericytoma-like pattern. A 2-day-old Japanese boy presented with multiple hemispherical nodules on the extremities and back. There was a biphasic histological growth in the dermis, accompanied by a hemangiopericytoma-like pattern with antler-like branching vessels. Tumor cells were oval to spindle-shaped myoid cells with bland appearance. Immunohistochemically, vimentin, calponin and CD34 were positive, while α-smooth muscle actin, h-caldesmon, HHF35 and desmin were negative. Although CD34 was positive, the present case could be diagnosed as infantile myofibromatosis. Myopericytoma, myofibroma/myofibromatosis, glomus tumor, glomangiopericytoma and angioleiomyoma share a continuous spectrum of benign hemangiopericytoma-like pattern tumors. Myofibroma/myofibromatosis is nearly included in myopericytoma among pericytic (perivascular) tumors, and could be positive for CD34. Several immunohistochemical panels of smooth muscle markers are needed for the diagnosis of pericytic (perivascular) tumors.
Linear IgA bullous dermatosis (LABD) is a rare autoimmune bullous disorder characterized by linear deposits of IgA at the basement membrane zone (BMZ) and/or by circulating IgA anti-BMZ antibodies. Comparing with other immuno-bullous diseases, LABD represents a heterogeneous disease entity with diversity of pathogenic IgA autoantibodies to different hemidesmosomal antigens and an association with malignancies and occasional drug use. We herein present an 82-year-old Japanese man with LABD, whose indirect immunofluorescence using 1M NaCl-split skin showed positive staining for IgA at the dermal side alone. Fluorescence overlay antigen mapping using laser scanning confocal microscopy (FOAM-LSCM) was employed to examine the in vivo bound patient's IgA, which was specific for type VII collagen (COL7), a prominent antigen of the sublamina densa. One year later, he developed malignant lymphoma, suggesting the diagnosis of paraneoplastic LABD. We reviewed 32 cases of sublamina-densa type LABD with anti-COL7 IgA antibodies thus far reported in the literature to compare the clinicopathological characteristics of this rare disease variant and emphasize that COL7 is the main autoantigen in sublamina densa disease.
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