Connective tissue nevi: an entity revisited.

BACKGROUND: Connective tissue nevi (CTN) may be isolated, either sporadic or hereditary, or syndromic as in the Buschke-Ollendorff syndrome. Few publications have addressed the variable clinical and histopathologic expression of these benign hamartomas. OBJECTIVE: We sought to characterize the clinical and histopathologic features of CTN and to highlight a spectrum of clinical disease. METHODS: We carried out a retrospective study of cases selected after strict clinical and histopathologic confirmation of the diagnosis. RESULTS: A total of 33 patients with CTN were included. The average age of onset was 2 years. Three clinical forms were distinguished: type A with lesions at a single site, with one case presenting as an ulcerated infiltrated plaque; type B with two or more sites of involvement; and type C with unusually severe infiltration with functional impairment of a limb. Histopathologic examination of lesional biopsy specimens showed 10 collagenomas, one elastoma, 18 mixed CTN, and an increased number of fibroblasts in 4 cases. No correlation between clinical type and histopathologic findings was observed. LIMITATION: This was a descriptive case series. CONCLUSIONS: CTN comprise a clinical spectrum ranging from isolated papules to unusually severe aggressive plaques with monomelic involvement. The histopathologic features are heterogeneous and include a newly described variant, which we name "cellular CTN" because of the increased number of fibroblasts.

The contribution of large genomic deletions at the CDKN2A locus to the burden of familial melanoma.

Mutations in two genes encoding cell cycle regulatory proteins have been shown to cause familial cutaneous malignant melanoma (CMM). About 20% of melanoma-prone families bear a point mutation in the CDKN2A locus at 9p21, which encodes two unrelated proteins, p16(INK4a) and p14(ARF). Rare mutations in CDK4 have also been linked to the disease. Although the CDKN2A gene has been shown to be the major melanoma predisposing gene, there remains a significant proportion of melanoma kindreds linked to 9p21 in which germline mutations of CDKN2A have not been identified through direct exon sequencing. The purpose of this study was to assess the contribution of large rearrangements in CDKN2A to the disease in melanoma-prone families using multiplex ligation-dependent probe amplification. We examined 214 patients from independent pedigrees with at least two CMM cases. All had been tested for CDKN2A and CDK4 point mutation, and 47 were found positive. Among the remaining 167 negative patients, one carried a novel genomic deletion of CDKN2A exon 2. Overall, genomic deletions represented 2.1% of total mutations in this series (1 of 48), confirming that they explain a very small proportion of CMM susceptibility. In addition, we excluded a new gene on 9p21, KLHL9, as being a major CMM gene.