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The clinical and histopathological features of herpes zoster (HZ) are usually straightforward. Atypical histological presentations, in the absence of the classical viral cytopathic changes, are well documented and can make the diagnosis of HZ extremely difficult. Herein, we review the existing literature on atypical cutaneous histological manifestations of the disease, with emphasis on the subtle clues, use of immunohistochemistry, and potential pitfalls. [ABSTRACT FROM AUTHOR]

Aims: Dermal hyperneury is defined as the hypertrophy of small nerves in the dermis. It has been described in a variety of settings. We present a series of nine new cases with a distinctive clinical presentation and review the existing literature. The aim of the study was to summarise the clinical, histopathological and immunohistochemical findings in a case series of dermal hyperneury with unique clinical presentation. Methods and results: Nine cases were identified from the referral practice of one of the authors. Clinical characteristics, including demographic details, were collated. The histopathological features and novel immunohistochemical findings were analysed. Four cases presented with multiple skin lesions. Clinical evaluation revealed no associated syndromic stigmata. The histology in all cases was that of dermal hyperneury. Immunohistochemistry for phosphatase and tensin homologue (PTEN) and RET was supportive of the lack of syndromic association. Conclusion: The presentation of dermal hyperneury with multiple cutaneous lesions and no syndromic associations is distinctive, and no study with PTEN and RET immunohistochemistry has previously been reported. Comparisons with recent reports of multiple non‐syndromic mucocutaneous neuromas are discussed. [ABSTRACT FROM AUTHOR]

Background: Few histologic studies describe the histopathologic aspects of scleromyxedema.Objective: We sought to describe the histopathologic and immunohistochemical features of scleromyxedema in a large series of patients.Methods: We studied all the cases with scleromyxedema diagnosed between 2000 and 2014 at participating centers. Sections with hematoxylin-eosin and special stains were examined. Immunohistochemistry for CD3, CD4, CD8, CD20, CD68, and factor XIIIa was performed in 10 cases.Results: A total of 44 skin biopsy specimens from 34 patients were reviewed. Two different histopathologic patterns were observed: the classic microscopic triad (dermal mucin deposition, fibroblast proliferation, fibrosis) was identified in 34 specimens, whereas an interstitial granuloma annulare-like pattern was found in 10 specimens. A superficial perivascular infiltrate with T lymphocytes was found in all specimens whereas an interstitial proliferation of CD68(+) epithelioid cells was identified in the 10 specimens with an interstitial granuloma annulare-like pattern. Elastic fibers were largely lost, explaining the redundant folds of the disease.Limitations: This was a retrospective study.Conclusions: Scleromyxedema shows 2 histopathologic patterns, including the classic type with the microscopic triad of mucin, fibroblast proliferation and fibrosis, and an interstitial granuloma annulare-like pattern. Recognition of these histologic presentations expands the spectrum of scleromyxedema and highlights the difficulty in diagnosing this disabling condition in the absence of a clinicopathological correlation. [ABSTRACT FROM AUTHOR]

Aims: Epithelioid malignant peripheral nerve sheath tumour (E-MPNST) is a distinctive variant of malignant peripheral nerve sheath tumour characterized by the predominance of epithelioid cells, diffuse S100 positivity and infrequent association with neurofibromatosis type 1. The aim of this study was to further delineate clinicopathological features of cutaneous E-MPNST, correlate them with disease outcome and discuss differential diagnosis. Methods and results: We analysed 11 cutaneous E-MPNSTs (six males, five females, median age 49 years, median size 1.6 cm). Tumours showed a predilection for lower extremities (45%) and trunk (45%), followed by upper extremity (9%). Follow-up was available for nine of 11 patients (range 24-100 months, median 52 months). Four patients had an uneventful clinical course (44%), two developed local recurrence(s) (22%) and three died due to disseminated disease (33%). No histological parameters were found to predict local recurrence(s), development of distant metastases or disease outcome, including size, percentage of epithelioid component, number of mitoses per 10 high-power fields, degree of nuclear atypia or site of occurrence (dermis, dermis/ subcutis, subcutis) (P > 0.05). Immunohistochemically, all tumours were diffusely S100-positive, with a subset displaying loss of integrase interactor 1 (INI1) expression (50%). Conclusions: Cutaneous E-MPNST has the potential to pursue an aggressive clinical course, associated with wide dissemination and unfavourable disease outcome. [ABSTRACT FROM AUTHOR]

Aims Aggressive epidermotropic cutaneous CD8+ lymphoma is currently afforded provisional status in the WHO classification of lymphomas. An EORTC Workshop was convened to describe in detail the features of this putative neoplasm and evaluate its nosological status with respect to other cutaneous CD8+ lymphomas. Methods and results Sixty-one CD8+ cases were analysed at the workshop; clinical details, often with photographs, histological sections, immunohistochemical results, treatment and patient outcome were discussed and recorded. Eighteen cases had distinct features and conformed to the diagnosis of aggressive epidermotropic cutaneous CD8+ lymphoma. The patients typically present with widespread plaques and tumours, often ulcerated and haemorrhagic, and histologically have striking pagetoid epidermotrophism. A CD8+/ CD45 RA+/ CD45 RO−/ CD2−/ CD5−/ CD56− phenotype, with one or more cytotoxic markers, was found in seven of 18 patients, with a very similar phenotype in the remainder. The tumours seldom involve lymph nodes, but mucosal and central nervous system involvement are not uncommon. The prognosis is poor, with a median survival of 12 months. Examples of CD8+ mycosis fungoides, lymphomatoid papulosis and Woringer-Kolopp disease presented the typical features well documented in the CD4+ forms of those diseases. Conclusions Aggressive epidermotropic cutaneous CD8+ lymphoma is a distinct lymphoma that warrants inclusion as a distinct entity in future revisions of lymphoma classifications. [ABSTRACT FROM AUTHOR]

Aims Unusual cytoplasmic alterations have recently been reported in poorly differentiated cutaneous angiosarcoma, making an accurate diagnosis challenging. As these tumours remain poorly documented, we aimed to study their clinicopathological characteristics more comprehensively. Methods and results Six cutaneous angiosarcomas with unusual cytoplasmic alterations were identified from referral files. All tumours arose as nodules or plaques (range: 05-195 mm) on sun-damaged skin of the head and neck of elderly males (median age: 76.5 years). Histologically, the tumours were composed of enlarged epithelioid cells showing prominent signet ring ( n = 3), foam ( n = 2) or granular cell ( n = 1) change. Vasoformative elements were only focally noted. By immunohistochemistry, all tumours expressed CD31 and avian v-ets erythroblastosis virus E26 oncogene homologue ( ERG). Foam cell change was associated with additional expression of CD68 and CD163. Follow-up (median: 8 months) showed death from disease ( n = 1), death from a gastrointestinal bleed ( n = 1), and a cutaneous metastasis ( n = 1). Only two patients are alive with no evidence of disease. Conclusions Our findings outline the morphological spectrum of cytoplasmic change in cutaneous angiosarcoma. Awareness and a high degree of suspicion in the context of tumours affecting sun-damaged skin of the elderly are necessary to direct appropriate immunohistochemical work-up with inclusion of the endothelial cell markers CD31 and ERG. [ABSTRACT FROM AUTHOR]

A granulomatous tissue response may be observed in untreated, long-standing lesions of secondary syphilis. In addition to poorly defined granulomatous inflammation, leprosy-like sarcoidal and palisaded granulomatous inflammation has been documented in literature reports of lues. Herein, we report a 47-year-old man who presented with a 3-month history of a generalized non-pruritic macular and papular rash located on the trunk and extremities. Histopathologically, there was an interstitial arrangement of histiocytes with occasional multinucleated giant cells positioned among collagen bundles without associated necrosis, thereby closely mimicking interstitial granuloma annulare. A clue to the diagnosis was the presence of admixed plasma cells. To the best of our knowledge, this is the first reported case of secondary syphilis showing an interstitial granulomatous pattern mimicking interstitial granuloma annulare. Sezer E, Luzar B, Calonje E. Secondary syphilis with an interstitial granuloma annulare-like histopathologic pattern. [ABSTRACT FROM AUTHOR]

The present manuscript gives emphasis on recognizing different morphological variants of atypical fibroxanthoma (AFX), on validation of immunohistochemical markers and on discussing potential diagnostic pitfalls. Material and methods: Histological features analyzed in 66 AFXs were: ulceration, morphological variants, growth pattern, location in the skin and vascular/perineural invasion. The antibodies used were CK-MNF116, CK-AE1/AE3, S100, smooth muscle actin, desmin, CD31 and EMA. Results: The study included 59 males, 7 females, aged 55–95 years, mean 77 years. All developed on sun damaged skin. Ulceration was present in 50%. Morphological patterns were pleomorphic spindle and epithelioid cells (60.6%), predominantly spindle cells (19.7%), purely spindle-cells (13.6%), and predominantly epithelioid cells (6.1%). Most were localized in the dermis (57.6%). An expansile (36.4%) rather than infiltrative (6.1%) growth into superficial subcutis was also noted. No vascular/perineural invasion was seen. Additional changes were hemorrhagic and pseudoangiomatous areas (24.2%), granular cell change (22.7%), keloid-like areas (9.1%), myxoid change (7.6%), osteoclast-like giant cells (6.1%) and clear cell change (4.6%). AFXs were consistently negative for S100, CK-MNF116, CK-AE1/AE3 and desmin. Focal positivity for SMA (45.2%), EMA (24.4%) and CD 31 (9.5%) was seen. Conclusions: A diagnosis of AFX is still made by exclusion of other malignant neoplasms with similar morphology. Immunohistochemistry plays a crucial role in this distinction, but can also be misleading. This study expands the spectrum of non-vascular CD31 positive tumors. Luzar B, Calonje E. Morphological and immunohistochemical characteristics of atypical fibroxanthoma with a special emphasis on potential diagnostic pitfalls. [ABSTRACT FROM AUTHOR]

Summary: Low-grade fibromyxoid sarcoma is a soft tissue sarcoma with recurrent and low metastatic potential, which has characteristic FUS-CREB3L2 or FUS-CREB3L1 fusions. Perineurioma is a peripheral nerve sheath neoplasm, which is usually benign. Low-grade fibromyxoid sarcoma and perineurioma can appear morphologically similar, particularly in small biopsy specimens, and distinction between the 2 entities is important for appropriate treatment. Low-grade fibromyxoid sarcoma is negative for most immunohistochemical markers, whereas perineuriomas stain variably for epithelial membrane antigen, CD34 and claudin-1, a tight-junction associated protein. We studied 15 cases of genetically proven low-grade fibromyxoid sarcoma that at least focally resembled perineurioma, with antibodies to claudin-1 and epithelial membrane antigen. Of these, 11 showed positivity for epithelial membrane antigen and all 15 were positive for claudin-1; in all cases, expression of claudin-1 was equal to or greater than the corresponding epithelial membrane antigen expression. This study emphasizes that claudin-1 is significantly expressed in low-grade fibromyxoid sarcomas. This has implications toward the accurate diagnosis of both tumors, and, as positivity for claudin-1 in low-grade fibromyxoid sarcoma is not previously documented, suggests that there might be underdiagnosis of low-grade fibromyxoid sarcoma. Although positivity for claudin-1 remains useful as an adjunct marker for perineurioma, it should be taken in context with clinical findings, morphology, and the additional immunoprofile. [Copyright &y& Elsevier]

Eccrine porocarcinoma is an uncommon sweat gland malignancy. To the best of our knowledge, there has been no report in the English literature of porocarcinoma with predominantly undifferentiated sarcomatous change. We present two cases of sarcomatoid eccrine porocarcinoma associated with a benign poroma. Case 1 pertained to an 82-year-old woman with an ulcerated chest wall tumor, and Case 2 was that of a 74-year-old woman who presented with an ulcerated plaque in the lower leg. Case 1 showed an unusual pseudo-angiosarcomatous morphology with spindle cells dissecting through collagen bundles and forming vascular like channels. Case 2 revealed high-grade malignant spindle cells with focal evidence of ductal differentiation. In both the cases, benign poromatous elements were histologically evident. Immunohistochemistry performed showed pancytokeratin positivity in spindle cells of both lesions. Epithelial membrane antigen and carcino-embryonic antigen positivity in the malignant ductal elements and focal smooth muscle actin staining of the spindle cells were demonstrated in Case 2. A brief review of relevant literature is presented. [ABSTRACT FROM AUTHOR]

Symplastic hemangioma is characterized by degenerative atypia of vascular smooth muscle and interstitial cells within a pre-existing vascular lesion with minimal endothelial cell atypia. We describe an additional two cases of this distinctive but poorly recognized entity. On histology, both lesions revealed a cirsoid aneurysm-type appearance with thick-walled and variably dilated blood vessels. The vascular endothelial cells showed mild nuclear hyperchromasia with no multilayering or mitoses. The atypical cells, either located within the vascular smooth muscle wall or within the interstitium, were spindle or epithelioid with varying degrees of hyperchromasia, nuclear enlargement, pleomorphism, and multinucleation. Perivascular hemorrhage, vascular thrombosis, and focal papillary endothelial hyperplasia were uniformly present. The variably fibrous to edematous stroma showed hemosiderin deposits and a mononuclear inflammatory infiltrate. Clusters of adipocytes were present within the superficial dermis. Rare atypical mitoses and occasional bizarre lipoblast-like stromal cells were identified in one tumor. Immunohistochemistry showed focal smooth muscle actin positivity in the pleomorphic cells of the vascular walls. CD68 and CD34 stained occasional stromal cells in the interstitial location. Both the cases showed no recurrence. The bizarre cytologic changes are interpreted as degenerative in nature and probably akin to that observed in ancient schwannoma and uterine symplastic leiomyoma. [ABSTRACT FROM AUTHOR]

Mutations inβ-catenin are present in benign pilomatrixomas.β-catenin is a downstream effector in the WNT-signalling pathway, acting as a signal for differentiation and proliferation. Mutations inCTNNB1, the gene encodingβ-catenin, are present in a wide variety of benign and malignant neoplasms. We examinedβ-catenin in a series of pilomatrix carcinomas (15 cases) by using immunohistochemistry and DNA sequencing of exon 3 fromCTNNB1, and compared these to a series of benign pilomatrixomas (13 cases). All 11 pilomatrix carcinomas available for examination showed nuclear localization ofβ-catenin and mutations in exon 3 similar to those demonstrated in benign pilomatrixomas. Two of 11 pilomatrix carcinomas showed significant nuclear accumulation of p53, whereas this was absent in all 13 benign pilomatrixomas. Expression of nuclear cyclin D1 was similar in both benign pilomatrixomas and pilomatrix carcinomas. Clinical follow-up from the 15 malignant cases reported in this study and by others indicates that wide excision offers superior control of local recurrence, compared to simple excision. Immunohistochemical and molecular analysis ofβ-catenin reveals that both pilomatrix carcinomas and benign pilomatrixomas harbour mutations inβ-catenin. This implies a common initial pathogenesis and is compatible with the proposition that pilomatrix carcinomas may at least on occasion arise from their benign counterparts.Lazar AJF, Calonje E, Grayson W, Dei Tos AP, Mihm Jr MC, Redston M, McKee PH. Pilomatrix carcinomas contain mutations inCTNNB1, the gene encodingβ-catenin. [ABSTRACT FROM AUTHOR]

We report a series of five cases of dermatofibrosarcoma protuberans, four of which were fibrosarcomatous and all of which showed histologic and immunohistochemical evidence of focal myoid/myofibroblastic differentiation (accounting for up to 5% of each tumor). These lesions were identified amongst 208 cases of dermatofibrosarcoma protuberans including 24 examples of the fibrosarcomatous variant. Three of the five patients were male and two were females: all were adults (37-72 years). One case arose on the scalp and two cases each on the abdominal wall and upper trunk. All tumors were less than 5cm in diameter and preoperative duration ranged from 2 months to 10 years. In three cases with follow-up there was no recurrence. Histologically, all tumors were typical fibrosarcomatous or ordinary dermatofibrosarcoma protuberans but for the presence of scattered to confluent nodules and bundles of eosinophilic spindle cells associated with well-defined cytoplasmic margins and vesicular nuclei associated with focal stromal hyalinization. While the typical dermatofibrosarcoma protuberans areas were CD34 positive, the myoid areas were negative for this antibody and positive for smooth muscle actin and pan-muscle actin. All tumors were desmin negative. Recognition of myofibroblastic differentiation in fibrosarcomatous dermatofibrosarcoma protuberans is important not only because it gives support to the theory of a fibroblastic/myofibroblastic line of differentiation of this type of tumor, but also because it might be a source of confusion with other myofibroblastic lesions (e.g. myofibromatosis, adult myofibroma), especially when small biopsies are evaluated. [ABSTRACT FROM AUTHOR]

The article presents the author's reply to comments made by physician Carlos Diaz-Cascajo on the article on myoid nodules in dermatofibrosarcoma protuberans (DFSP) and its fibrosarcomatous variant. As stated in the paper, authors were at pains to try and exclude that these nodules originated from vessel walls. Aside from simple morphological assessment in this regard, it is notable that such nodules are not desmin positive and that, at least subjectively, these nodules are often greater in number than the usual constituent larger vessels that one would expect in a DFSP.