Subungual onycholemmal cyst of the toenail mimicking subungual melanoma.

This report highlights a rare case of a woman with horizontal ridging and tenderness of the right great toenail associated with dyspigmentation of 5 years' duration. Histopathology revealed a cystic structure with an epithelial lining mostly reminiscent of an isthmus-catagen cyst admixed with the presence of both an intermittent, focal granular layer and an eosinophilic cuticle surrounding pink, laminated keratin, most consistent with a diagnosis of subungual onycholemmal cyst (SOC). It is a rare and distinctive nail abnormality occurring in the dermis of the nail bed. We present a case of an SOC in the toenail mimicking subungual malignant melanoma, which may be an underrecognized and common entity that must be considered when discussing tumors of the nail unit, especially subungual melanoma.

Weightlifter's Nodule: A New Variant of Athlete's Nodule.

A 17-year-old high school football player presented to our dermatology clinic complaining of two asymptomatic lumps on the upper part of his back. The first lump was noticed on the right side of the upper aspect of his back following a weightlifting session. The second lump appeared on the left side of the upper part of his back several weeks later. The patient's personal and family medical history was unremarkable. Physical examination revealed an ill-defined, firm, mobile subcutaneous nodule measuring approximately 3 cm on the right upper part of the back and a similar but smaller nodule on the left upper portion of the back (Figure 1). The location of the lesions corresponded to the areas of maximal pressure produced by a squat bar that he uses frequently during weightlifting (Figure 2). Histologic analysis of the right lesion revealed a markedly expanded dermis caused by a striking increase in the number of collagen bundles that were relatively normal in thickness, accompanied by a subtle increase in the number of fibroblasts (Figure 3). In some foci, fibroplasia along with increased deposition of mucin further contributed to the expansion of the dermis (Figure 3). Although the process spanned the entire dermis, it was more pronounced in the deep reticular dermis, particularly near the subcutis as collagen bundles were arranged in a more haphazard array in this region. Verhoeff-Van Gieson stain revealed diminished and fragmented elastic fibers within some of the involved areas. This reactive fibrosis can be seen in athlete's nodules as a result of repetitive blunt pressure. We proposed a diagnosis of weightlifter's nodule to further classify these lesions and the patient was instructed to discontinue associated weightlifting activities.

Giant metastatic Merkel cell carcinoma.

A 68-year-old man presented with a rapidly growing, asymptomatic mass on his left mid-back for the past 3 months. The patient's medical history revealed an intentional 60-pound weight loss over the previous 2 years along with smoking approximately 1 pack of cigarettes per day. On physical examination, a fungating, 11-cm red tumor with palpable broader underlying extension (23 cm total) was present on the left mid-back with distinct red dermal nodules in a dermatomal distribution. In close proximity were two ulcerated nodules, proven histologically to be basal cell carcinomas. In the left groin was massive, fixed lymphadenopathy. A punch biopsy of the tumor was performed, which showed a dense infiltrate of small, round hyperchromatic blue cells that stained positive for CD 56 and pancytokeratin in a perinuclear dot pattern. Tumor cells were negative for CK20, TTF, CK7, and LCA.

The necrolytic erythemas: a continuous spectrum?

The necrolytic erythemas is a group of disorders with similar histologic and clinical features. The objective of this case report is to present a patient with features of both necrolytic migratory erythema (NME) and necrolytic acral erythema (NAE). These 2 entities appear more likely to be on a spectrum caused by the same underlying process of abnormal liver function and glucagon metabolism.

Porokeratosis ptychotropica: a clinically distinct variant of porokeratosis.

Porokeratosis represents a spectrum of clinical disease. Multiple variants have been described including porokeratosis ptychotropica, a rare subtype. The clinical presentation of porokeratosis ptychotropica frequently resembles an inflammatory perianal disease. We report a patient with porokeratosis ptychotropica with coexistent disseminated superficial actinic porokeratosis. We review the current literature on porokeratosis ptychotropica including the clinical presentation, histopathology, cause, and pathogenesis of this rare variant of porokeratosis.

Genetic heterogeneity in erythrokeratodermia variabilis: novel mutations in the connexin gene GJB4 (Cx30.3) and genotype-phenotype correlations.

Erythrokeratodermia variabilis is an autosomal dominant genodermatosis characterized by persistent plaque-like or generalized hyperkeratosis and transient red patches of variable size, shape, and location. The disorder maps to a cluster of connexin genes on chromosome 1p34-p35.1 and, in a subset of families, results from mutations in the gene GJB3 encoding the gap junction protein connexin-31 (Cx31). A recent report suggested the involvement of another connexin gene (GJB4) in the etiology of erythrokeratodermia variabilis. In this study, we sequenced the coding region of GJB4 in 13 unrelated erythrokeratodermia variabilis families without detectable mutations in GJB3. Mutation analysis revealed six distinct missense mutations in five families and a sporadic case of erythrokeratodermia variabilis, all of which were not found in controls. Mutation G12D, identified in an extended Dutch family, lies in the predicted amino-terminus and may interfere with the flexibility of this domain, connexin selectivity, or gating polarity of gap junction channels. Other mutations (R22H, T85P, F137L, F189Y) were located in the transmembrane domains of Cx30.3, and are predicted to hinder regulation of voltage gating or alter the kinetics of channel closure. Affected individuals of two unrelated families harbored point mutations leading to amino acid substitution F137L, which was also reported in GJB3, yet the extent and severity of hyperkeratosis was milder compared to the corresponding mutation in GJB3. Two mutations (T85P, F137L) were associated with the occurrence of rapidly changing erythematous patches with prominent, circinate, or gyrate borders in affected children but not in adults, supporting the notion that this feature is specific to Cx30.3 defects. Nevertheless, we observed highly variable intrafamilial phenotypes, suggesting the strong influence of modifying genetic and epigenetic factors. In addition to pathogenic mutations, we identified several missense mutations and a 4 bp deletion within the GJB4 coding region, which might represent either inconsequential polymorphisms or recessive mutations. In conclusion, our results demonstrate genetic heterogeneity in erythrokeratodermia variabilis, and emphasize that intercellular communication mediated by both Cx31 and Cx30.3 is crucial for epidermal differentiation.