Paraneoplastic pemphigus associated with Castleman's disease: usefulness of the laboratory of autoimmunity in the diagnosis of this disease.

We report on a case of paraneoplastic pemphigus associated with Castleman's disease. Clinical pathologic features were not conclusive. Diagnosis was established thanks to the detection of seric autoantibodies directed against intercellular substance by indirect immunofluorescence on monkey esophagus. The positive result of this test prompted us to reevaluate the patient and to detect the occult neoplasia. The demonstration of autoantibodies against plakins is the key marker of this disease but depends on tests that may not be readily available in many places like immunoprecipitation, immunoblotting, or indirect immunofluorescence over rat bladder. In this setting, tests like indirect immunofluorescence over monkey esophagus, although unspecific, may aid in reaching the appropriate diagnosis. This case illustrates the importance of the laboratory of autoimmunity in the diagnosis of this type of pemphigus.

Giant cell fibroblastoma. New histological observations.

Giant cell fibroblastoma is a rare mesenchymal neoplasm of unknown origin and uncertain clinical course. The neoplasm has been considered by some authors as a juvenile variant of dermatofibrosarcoma protuberans. We report a patient with giant cell fibroblastoma, now 28 months following surgical removal, in which the neoplasm was characterized histologically by a proliferation of spindle-shaped cells intermixed with pseudovascular channels called "angiectoid spaces." The spaces were lined by large cells with pleomorphic nuclei intermixed with multinucleated cells. Immunohistochemically, the tumor stained diffusely for vimentin and CD34, a surface glycoprotein expressed by some mesenchymal neoplasms including dermatofibrosarcoma protuberans. We postulate a mechanism of formation of the angiectoid spaces based on histopathological findings in serially sectioned portions of the neoplasm. Positive staining of tumor cells for CD34 supports a possible relationship of the neoplasms with dermatofibrosarcoma protuberans.

Comparison of p53 expression in dermatofibrosarcoma protuberans and dermatofibroma: lack of correlation with proliferation rate.

p53 protein plays an important role in control of cell proliferation by suppressing proliferation of cells with DNA damage. Mutations of the p53 gene increase the stability of the encoded nonfunctional protein which accumulates in the nuclei, allowing it to be detectable by immunohistochemistry. Mutant p53 protein has been observed in preneoplastic and neoplastic conditions supporting its role in the development of some human cancers. In this immunohistochemical study, we examined p53 expression in 12 Dermatofibrosarcoma Protuberans (DFSP) and 10 Dermatofibromas (DF). Results were compared with the cellular proliferation rate by using the monoclonal antibody Mib-1 which detects Ki-67 antigen expression. Nuclear accumulation of the p53 protein was observed in 11 DFSP. All DF were negative for p53. No statistical correlation could be established between p53 and Mib-1 staining in our cases. We conclude that mutations of the p53 gene may be involved in the molecular pathogenesis of DFSP but not of DF. Mib-1 index can not be successfully used to distinguish DFSP from DF.