No abstract

Some melanocytic tumors can be histologically ambiguous causing diagnostic difficulty, which could lead to overtreatment of benign lesions with an unwarranted psychological distress or undertreatment of malignant cancers. Previously, we demonstrated that significantly decreased miR-211 expression in melanomas compared with melanocytic nevi could accurately discriminate malignant from benign tumors. Herein we show microRNA in situ hybridization for fluorescent detection of miR-211, suitable for paraffin-embedded tissues in 109 primary melanocytic tumors. miR-211 expression was significantly lower in melanomas vs nevi (P<0.0001), and receiver operating characteristic curve (area under the curve=0.862) accurately discriminated melanomas from nevi with 90% sensitivity and 86.2% specificity. Qualitatively, all dysplastic nevi expressed miR-211 at high (86%) and low (14%) levels, independent of the degree of nuclear atypia. All 35 melanocytic tumors with Spitz morphology expressed miR-211 independent of morphological classification, where clinical follow-up of these patients showed no recurrence at the site or metastasis in mean and median of 3 (ranging 2-5) years. Moreover, a decision tree learning analysis selected age and miR-211 miRNA in situ hybridization as the predictive variables for benign or malignant outcome in 88 patients correctly classified 92% (81 out of 88) of cases as proven by receiver operating characteristic curve (area under the curve=0.9029). These results support miR-211 as a leading miRNA candidate for melanoma diagnosis and miRNA in situ hybridization as a uniquely uncomplicated ancillary test.

Histologic differentiation of melanoma in situ (MIS) from solar keratosis on chronically sun-damaged skin is challenging. The first-line immunostain is usually MART-1/Melan-A, which can exaggerate the epidermal melanocytes, causing a diagnostic pitfall for MIS. By comparing MART-1 and SOX10 immunostaining, we scored the percentage of epidermal melanocytes per 2-mm diameter fields in pigmented actinic keratosis (n = 16), lichenoid keratosis (n = 7), junctional melanocytic nevus (n = 6), keratosis with atypical melanocytic proliferation (n = 17) and MIS (n = 10). These cases represented an older population (68 years median age) and the head and neck (50%) was the most common anatomic site. MART-1 score was significantly higher than SOX10 (P value <.05) in solar keratoses, but showed no difference in detecting melanocytic proliferations, demonstrating their equal detection rate of melanocytes. The sensitivity of both MART-1 and SOX10 was 100%, while their specificities were 17% and 96%, respectively. These results show that SOX10 is more specific than MART-1 in distinguishing epidermal melanocytes on sun-damaged skin by avoiding overdiagnosis of melanoma.

We present a rare case of pagetoid reticulosis arising in a five year old white boy. He had a history of a large chronic erythematous, scaly patch on his left buttock that had shown intermittent partial response to a topical anti-fungal medication. A punch biopsy revealed dramatic epidermal hyperplasia, with parakeratosis and prominent exocytosis of single and clustered mononuclear cells (Pautrier's microabscesses) into the epidermis. Some of these exhibited hyperchromatic nuclei with irregular contours. They stained prominently for CD3, CD4 and CD8, with a predominance of CD8 + cells. T cell receptor gene rearrangement by PCR was negative for a clonal process on a second biopsy that was sub diagnostic on routine sections.Pagetoid reticulosis is an indolent, unilesional variant of mycosis fungoides, in which the atypical T cells may express a CD4−/CD8+ phenotype. This is in contrast to primary cutaneous epidermotropic CD8+ cytotoxic T-cell lymphoma, which is often very aggressive with a poor outcome. Pagetoid reticulosis is exceedingly rare in children and adolescents. Two features predict a benign course in this 5 year old child: the unilesional clinical presentation and the CD8 predominance of the epidermal lymphocytes.