Abstract Melanoma can develop in a congenital melanocytic nevus (CMN). In fact, a large CMN is associated with a high risk of developing melanoma. Although melanomas arising from CMNs are thought to have a pathogenesis distinct from conventional melanomas, no studies have been conducted on the evolution or tumor heterogeneity of CMN melanomas. We applied multi‐region whole‐exome sequencing to investigate the clonal nature of driver events and evolutionary processes in CMNs and melanomas arising from CMNs. In two patients, we observed an independent subclonal evolution in cancerized fields of CMNs and chromosome 8q amplification in both melanomas arising from CMNs. The amplification of MYC, located in chromosome 8q, was correlated with the percentage of tumor cells expressing high levels of MYC protein detected in melanoma cells by immunohistochemistry. Our analysis suggests that each CMN cell may evolve sporadically and that amplification of MYC might be a key event for melanoma development in CMNs.
Dear Editor:
Porokeratosis is a primary disorder of epidermal keratinization, characterized by annular plaques with an atrophic center and hyperkeratotic edges1. Circumscribed palmar or plantar hypokeratosis (CPH) was first described in 2002 by Perez et al.2 Clinically, CPH presents as patches of depressed skin most commonly on the thenar or hypothenar areas of the palm in middle-aged or elderly individuals3.
A 65-year-old man presented with an asymptomatic skin lesion on the right palm for 1 year. He denied any history of trauma, burn, or exposure to a chemical agent. On physical examination, a 3-mm, well-demarcated, erythematous, and depressed macule was seen on the center of the right palm (Fig. 1). A 4-mm punch biopsy was performed for its diagnosis and excision. Microscopic examination revealed a stair-like decrease in the thickness of the stratum corneum, leading to a central area of thinning (Fig. 2A, B). These findings are analogous to CPH. However, there was a parakeratotic column (cornoid lamella) on the margin of the lesion. Moreover, below the cornoid lamella, the granular layer was thinned and vacuolated keratinocytes were present. The underlying upper dermis revealed mild inflammatory infiltrates. Although some features of the macule mimicked those of CPH, these clinical and histological findings were consistent with a diagnosis of porokeratosis. At his first follow-up, the palmar macule had clinically resolved after the punch biopsy.
Fig. 1
Atrophic circular macule measuring 3×3 mm with a well-demarcated border on the center of the right palm, and close-up view.
Fig. 2
(A) Histological analysis of the 4-mm punch biopsy specimen obtained from the patient shows an abrupt decrease in stratum corneum (H&E, ×40), (B) cornoid lamella on the margin of the lesion. And hypogranulosis and edematous changes of ...
The histopathologic patterns of porokeratosis are distinctive. A biopsy specimen from the margin of the lesion revealed hyperkeratotic stratum corneum with a thin column of poorly stained parakeratotic cells. The cornoid lamella is the hallmark of all porokeratosis variants4. The underlying keratinocytes are edematous with spongiosis, and the upper dermis may show lymphocytic infiltration. The granular layer underlying the cornoid lamella is either absent or markedly reduced but is of normal thickness in other areas of the lesion5. In the central part of porokeratosis, the epidermis may be normal, hyperplastic, or atrophic. Histopathologic findings in our case corresponded to these findings.
Since the first description of porokeratosis, different variants including porokeratosis of Mibelli (PM) and punctate porokeratosis (PP) have been subsequently recognized4. PM, the most common variant, is characterized by a single plaque or a small number of plaques of varying sizes, and it usually begins during infancy or childhood. The well-demarcated hyperkeratotic border is usually more than 1 mm in height5. Although our patient had a solitary lesion, he was middle-aged and the border of the lesion was thin. In contrast, PP is a rare variant of porokeratosis. It is characterized by multiple minute and discrete punctate, hyperkeratotic seed-like lesions, commonly surrounded by a thin raised margin located along the palmoplantar surfaces5. However, our patient only had a single lesion.
In conclusion, we diagnosed this case as porokeratosis. However, we could not classify this condition as being a particular variant of porokeratosis, like PM or PP. In addition, some clinical and pathologic features resembled CPH. We would like to present this unusual case, as it had partial features of both PM, and PP and mimicked CPH.
Dear Editor:
Onychomatricoma is a very rare tumor of the nail unit. It is originally reported to be a benign tumor of the nail matrix as the name implies1. However, histopathologically, it is a fibroepithelial tumor with well-established features. Recently, based on its histopathological and immunohistochemical features, the concept of epithelial onychogenic tumor with onychogenic mesenchyme is being suggested for this peculiar mixed tumor2. Nevertheless, the authors mention that the term onychomatricoma is short and sanctioned by usage, and justifies such statement.
We recently demonstrated the presence of specialized mesenchyme containing onychofibroblasts beneath the nail matrix and nail bed3,4. Based on this finding, we proposed new terminology onychodermis for specialized mesenchyme because it is histologically and immunohistochemically distinct from the dermis of other parts of the nail unit.
This study evaluates the relation of onychomatricoma to onychodermis in the nail unit we performed CD10 immunohistochemistry in one case of onychomatricoma sample (a kind gift from Dr Robert Baran and Dr Josette Andre). Immunohistochemical staining was performed using the monoclonal antibody of CD10 (1 : 50, clone 56C6; Novocastra, Newcastle, UK). Normal nail unit is being used as a control.
As reported previously, CD10 is strongly expressed in the onychodermis below the nail matrix and nail bed within normal nail unit (data not shown). In the onychomatricoma case, CD10 is being expressed diffusely in the stoma (Fig. 1).
Fig. 1
Immunohistochemical staining of CD10 in onychomatricoma. CD10 was diffusely expressed in the stroma of onychomatricoma. (A) Low-power view (×40), (B) highpower view (×200).
Onychomatricoma is a subungual tumor which consists of epithelial onychogenic tumor with onychogenic mesenchyme. Based on its components and location, the onychodermis, which is located below the nail matrix and nail bed, might be related to the occurrence of the onychomatricoma. In addition, in our case, the CD10, which is a marker of the onychodermis, is expressed in the stroma of the onychomatricoma, supporting that onychomatricoma might derive from the onychodermis. According to a previous study using organotypic cultures, the fibroblasts around the nail matrix induced hard keratin expressions in the non-nail-matrix keratinocytes through epithelial-mesenchymal interactions5. Thus, the onychodermis containing onychofibroblasts may play an important role in nail formation through epithelial-mesenchymal interactions. Epithelial lesion in onychomatricoma might be induced by mesenchymal tumor occurring in the onychodermis. To deduce, the onychodermis might be involved in the histogenesis of the onychomatricoma.
In conclusion, onychomatricoma seems to be closely related to the onychodermis. It might be a derivative from onychoderms.
The epidemiological and clinicopathological features of cutaneous lymphoma may vary by geographical area. However, only a few large-scale epidemiological studies of cutaneous lymphoma have been performed, mainly in the USA and Europe. This aim of this study was to determine the recent characteristics of cutaneous lymphoma in Korea according to the WHO/EORTC classification. A total of 422 patients with newly diagnosed cutaneous lymphoma from January 2009 to December 2013 comprising 293 cases of mature T-cell and natural killer (NK)-cell lymphoma and 39 cases of mature B-cell lymphoma were retrospectively reviewed. The incidence of mature B-cell lymphoma was lower in Korea than in Europe and the USA. Diffuse large B-cell lymphoma was more prevalent in Korea than in Western countries. The incidence of extranodal NK/T-cell lymphoma, nasal-type was higher in Korea than in Western countries and Japan.
Sarcoidosis is an idiopathic multisystem disease with various cutaneous presentations, and it is characterized by the presence of non-caseating granulomas in the affected organs. The specific manifestations are papules, plaques, nodules, ulcers and scar. We report here on a variant of sarcoidosis on a 71-year-old woman who showed an indurated plaque on the forearm. Her lesion's appearance was clinically similar to that of a morphea and the appearance of the lesion was unlike the commonly observed manifestations of sarcoidosis.
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