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Background: Loss of p53 tumor suppressor function is a critical step in the development of diverse malignancies, including skin cancers in nonimmunosuppressed patients where UV-specific p53 gene mutations have been identified. In tumors associated with human papillomavirus (HPV), such as cervical carcinoma, p53 may be inactivated instead by binding to a viral oncoprotein., Objective: Our purpose was to examine the hypothesis that HPV may play an analogous role in the development of posttransplant skin cancer., Methods: p53 Immunoreactivity, suggestive of p53 gene mutation, was examined by immunocytochemistry. Oncogenic HPV DNA was detected by polymerase chain reaction., Results: Comparable p53 immunoreactivity was seen in skin tumors from both transplant and nontransplant patients. HPV DNA was not demonstrated in any tumor specimen., Conclusion: Our data do not implicate oncogenic HPV in posttransplant skin cancer. p53 Gene mutation, rather than HPV-induced p53 degradation, may be more significant in the development of these tumors.

Background: Posttransplant lymphoma is closely associated with Epstein-Barr virus (EBV) infection and appears to have a predilection for extranodal sites. We describe four cases of primary cutaneous posttransplant lymphoma., Objective: Our aim was to determine cell lineage and any possible association with EBV in each case of cutaneous lymphoma., Methods: Tumor tissue was examined by light microscopy, immunohistochemistry, nonisotopic in situ hybridization and polymerase chain reaction., Results: The data were consistent with a diagnosis of EBV-associated cutaneous B-cell lymphoma in three cases and cutaneous T-cell lymphoma not associated with EBV in one case. No patient with B-cell lymphoma had extracutaneous involvement during a mean follow-up of 3.9 years. The patient with cutaneous T-cell lymphoma died of cerebral involvement 9 months after initial presentation., Conclusion: These data suggest a possible role for EBV infection in the origin of cutaneous B-cell lymphoma in immunosuppressed patients.

Cutaneous necrobiotic xanthogranuloma is rare and closely resembles widespread necrobiosis lipoidica. It is important to recognize this skin disorder because of its strong association with paraproteinemia and, in some cases, with a hematologic malignancy. We describe two patients with necrobiotic xanthogranuloma who are unusual in that they had no periorbital involvement, a feature previously believed to be diagnostic of this condition.

Background: Renal allograft transplantation is associated with an increased incidence of malignant melanoma. The development of excess melanocytic nevi may be an indicator of this risk., Objective: This study determines the prevalence of melanocytic nevi in children who have received renal allografts., Methods: Total and regional melanocytic nevi counts were made in 38 children (27 boys, 11 girls) with a renal allograft and in 38 individually age- and sex-matched healthy controls; counts were related to age, sex, skin type, and duration of immunosuppression., Results: There was a significant increase in the total number of nevi in the renal transplant group compared with the control group (p < 0.05), with most marked increases occurring on the back and at acral sites. A strong positive correlation between nevi count and duration of immunosuppression independent of age was observed (p < 0.005)., Conclusion: Excess numbers of melanocytic nevi occur in children with renal allografts. These patients constitute a risk group for malignant melanoma and require continued assessment.

Background: Epidermal dendritic cells (DCs) isolated from psoriasis possess greatly enhanced T lymphocyte-activating properties compared with DCs from normal skin, suggesting that DCs in psoriasis express surface antigens crucial for antigen presentation. These include beta 2-integrins and intercellular adhesion molecule (ICAM)-1., Objective: Our purpose was to determine DC phenotype in psoriatic compared with normal epidermis with respect to these molecules., Methods: Tissue sections were single labeled with a peroxidase antiperoxidase (PAP) immunohistochemical technique and double labeled where necessary with a combination of a PAP and an alkaline phosphatase-anti-alkaline phosphatase technique., Results: In psoriatic compared with normal skin, decreased numbers of DCs expressed CD1a (p less than 0.05), whereas increased numbers of DCs expressed class II major histocompatibility antigens (p less than 0.05). In normal skin positive staining for CD18 was not observed, whereas in psoriasis both CD1a+ and CD1a- DCs expressed beta 2-integrins, LFA-1 (CD11a/CD18), and gp 150/95 (CD11c/CD18). DCs in atopic dermatitis and lichen planus were also found to express beta 2-integrins. Neither MAC 1 (CD11b/CD18) nor ICAM-1 was observed on DCs., Conclusion: These data are consistent with either migration of dendritic antigen-presenting cells into the epidermis or in situ cytokine modulation of Langerhans cell phenotype in inflamed skin. Furthermore, they indicate that epidermal DCs in psoriasis and other cutaneous inflammatory diseases express molecules that are known to be crucial for Langerhans cell-driven T-cell activation in vitro.