Journal of cutaneous pathology
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Melastatin (TRPM1), a.k.a. transient receptor potential cation channel, subfamily M, member 1 (TRPM-1) regulates melanocyte differentiation and proliferation. TRPM1 is transcriptionally regulated by the essential melanocyte transcription factor MITF (microphthalmia-associated transcription factor). For the most part, MITF expression is preserved during melanoma progression, while TRPM1 mRNA expression decreases or is completely lost. The loss of TRPM1 is associated with melanomas that are more aggressive. ⋯ By CISH, TRPM1 mRNA expression is specific for melanocytes and strongly associated with MITF and tyrosinase expression, the latter implicating a mature melanocyte phenotype. However, in normal skin, TRPM1 mRNA expression appears to be dynamic, labeling most but not all melanocytes, with variable expression ostensibly related to local environmental factors.
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Review Case Reports
Non-sentinel lymph node involvement in a patient with an atypical Spitz tumor and a positive sentinel node. Report of a case and review of the literature.
We report a 20-year-old male patient with an atypical Spitz tumor, located in the dorsal aspect of his left hand, and a positive sentinel axillary lymph node. After lymphadenectomy, 1 of 23 non-sentinel lymph nodes excised was found to contain small multiple deposits of large spindle atypical melanocytes. Reviewing the pertinent literature, 5 of 29 patients with atypical Spitz tumors and positive sentinel nodes who had undergone lymphadenectomy have shown non-sentinel node involvement (17.2%), a proportion similar to that reported in melanoma patients. The exact nature of atypical Spitz tumors and the interpretation of cell deposits detected in sentinel nodes are still debated; data regarding the non-sentinel lymph node involvement in patients with atypical Spitz tumors may contribute to better understand the real biological potential of such tumors.
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Neural fibrolipoma, also known as lipofibromatous hamartoma of nerves and neurolipomatosis, is a rare subcutaneous benign lesion involving the upper extremity with a marked predilection for median nerve. In one-third of the cases, it is associated with macrodactyly (enlargement of one or several digits of hands or feet), diminished sensation, paraesthesias and compression neuropathy. A 23-year-old male presented with a gradually increasing mass in the right palm without associated macrodactyly or neurodeficit. ⋯ Limited excision was the mainstay of conservative treatment. Neural fibrolipomas are a rare entity. Knowledge of characteristic histological and radiological findings is necessary for diagnosis and treatment.
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Phytophotodermatitis (PPD) is a common phototoxic eruption, but very little information is available about its histological aspects, as the diagnosis is clinically established. ⋯ PPD can be successfully reproduced in rat skin. After 24 h spongiosis, vacuolization and keratinocyte necrosis are observed, clinically there are no changes. After 48 h, erythema appears with intra- and subepidermal blistering.