The diagnosis of autoimmune bullous dermatoses relies greatly on direct immunofluorescence (DIF) examination performed on frozen tissue sections, showing deposits of immunoglobulins and/or C3 on specific cutaneous structures. However, frozen material is not always available for DIF; therefore, alternative techniques are needed in the diagnostic procedure. We therefore tested the usefulness of C4d immunohistochemistry on formalin-fixed, paraffin-embedded tissue sections for the diagnosis of bullous pemphigoid (BP) and pemphigus (P). A retrospective immunohistochemical study was performed on biopsies of BP (n: 29) and P (n: 22, including 19 Pemphigus vulgaris and 3 paraneoplastic), submitted for routine histological examination and compared with DIF on the corresponding frozen sections. Twenty-five BP biopsies (86.2%) showed C4d deposits seen as a linear labeling along the dermal-epidermal junction and on the membrane of basal keratinocytes. Seventeen P biopsies (77.2%) showed C4d deposits in a classical "intercellular" pattern, predominating on the lower epidermal layers. The sensitivity, specificity, positive predictive value, and negative predictive value reached 86%, 98%, 96%, and 92% in BP, respectively and 77%, 98%, 94%, and 92% in P, respectively. Furthermore, in the cases where serological tests were available, the sensitivity of C4d detection was higher than that of enzyme-linked immunosorbent assay/indirect immunofluorescence in both BP (87% vs. 67%) and P (82% vs. 54.5%). We conclude that DIF on frozen sections still remains the gold standard for the immunopathological diagnosis of BP and P; however, in the absence of frozen material, C4d immunohistochemistry performed on routinely processed biopsy material can be of considerable help in confirming the diagnosis.
Milia-like idiopathic calcinosis cutis is a rare entity. Only 17 cases have been reported so far. Two-thirds of these have been associated with Down syndrome. We report the fifth case occurring in a child without Down syndrome. Milia-like idiopathic calcinosis cutis has long been regarded as a peculiar subtype of idiopathic calcinosis cutis. The pathogenesis of the disorder remains unclear.
p63 is an oncogene belonging to the p53 gene family. In normal human skin, p63 is expressed by the least-differentiated keratinocytes of the epidermis and its appendages, by myoepithelial cells of sweat glands, and by a wide variety of primary tumors arising therefrom. The expression of p63 by metastatic skin tumors has been more controversial. In this study, we assessed the usefulness of p63 detection in the differential diagnosis between primary and secondary (metastatic) skin tumors. The expression of p63 was studied in 45 cases of cutaneous metastases, mostly of known primary origin, and 94 benign and malignant epithelial primary skin tumors. p63 was expressed by 85 (89%) of 96 primary skin tumors and 5 (11%) of 45 cutaneous metastases. These results suggest that p63 may be a useful adjunct in the diagnosis of skin carcinomas; however, contrary to what has been previously claimed, expression of p63 does not rule out the metastatic origin of a cutaneous carcinoma.
The immunohistopathologic features of CPH suggest that an altered (accelerated) corneocyte desquamation process could be the main pathological mechanism underlying the development of lesions.
Porokeratoma (porokeratotic acanthoma) is a very recently described tumor-like acanthoma with features of porokeratosis (cornoid lamellation). We report herein a new case of this poorly known lesion that was studied immunohistochemically and discuss briefly its relationship with porokeratosis.
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