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Dedifferentiation and transdifferentiation are rare and only poorly understood phenomena in cutaneous melanoma. To study this disease more comprehensively we have retrieved 11 primary cutaneous melanomas from our pathology archives showing biphasic features characterized by a conventional melanoma and additional areas of de-/trans-differentiation as defined by a lack of immunohistochemical expression of all conventional melanocytic markers (S-100 protein, SOX10, Melan- A, and HMB-45). The clinical, histologic, and immunohistochemical findings were recorded and follow-up was obtained. The patients were mostly elderly (median: 81 years ; range: 42–86 years) without significant gender predilection, and the sun-exposed skin of the head and neck area was most commonly affected. The tumors were deeply invasive with a mean depth of 7 mm (range: 4–80 mm). The dedifferentiated component showed atypical fibroxanthoma-like features in the majority of cases (7), while additional rhabdomyosarcomatous and epithelial transdifferentiation was noted histologically and/or immunohistochemically in two tumors each. The background conventional melanoma component was of desmoplastic (4), superficial spreading (3), nodular (2), lentigo maligna (1), or spindle cell (1) types. For the seven patients with available follow-up data (median follow-up period of 25 months ; range: 8–36 months), two died from their disease, and three developed metastases. Next- generation sequencing of the cohort revealed somatic mutations of established melanoma drivers including mainly NF1 mutations (5) in the conventional component, which was also detected in the corresponding de-/trans-differentiated component. In summary, the diagnosis of primary cutaneous de-/trans-differentiated melanoma is challenging and depends on the morphologic identification of conventional melanoma. Molecular analysis is diagnostically helpful as the mutated gene profile is shared between the conventional and de-/trans-differentiated components. Importantly, de-/trans-differentiation does not appear to confer a more aggressive behavior.

A 77-year-old woman attended clinic for review of longstanding necrobiosis lipoidica. She reported a tender lesion on the left lower leg that had developed over 2 months. This had not responded to treatment with topical steroids, unlike all previous necrobiosis lipoidica-related ulcerations. On

Epidermolytic acanthoma is a rare benign lesion that most often presents as a solitary or multiple small papular lesions on the trunk, face, limbs or external male genitalia. Only a small number of cases have been reported occurring on the vulva and clinically and histologically they may mimic and be misdiagnosed as viral warts. We report 2 cases of multiple epidermolytic acanthomas localized to the vulva. Molecular tests (in situ hybridization and polymerase chain reaction) showed no evidence of human papillomavirus infection and p16 staining was negative. We stress the need for pathologists to consider epidermolytic acanthoma in the differential diagnosis of multiple vulval lesions resembling viral warts.

Introduction This survey examines regional variation in the diagnosis of keratoacanthoma (KA). Methods Twenty-three departments from Great Britain and Ireland were invited. The number of cases coded as KA or cutaneous SCC in the previous 12 months was retrieved. An SCC: KA ratio was calculated. Participants also provided free text responses. Results Seventeen departments replied. A total of 11 718 cases were included with a breakdown of 998 KA and 10 720 SCC. The mean SCC:KA ratio was 10.7:1, range (2.5:1 to 139:1). Free text responses are presented. Discussions An extreme variation in approach is highlighted by this survey. We believe a multidisciplinary team approach to the diagnosis of KA is essential. There seems to be a need for a carefully considered clinicopathological study, backed up by molecular studies, to better understand the natural biology of this diagnosis.

An unusual cervical adenocarcinoma is reported in a 50-year-old woman with a history of Peutz Jeghers syndrome. The carcinoma contained two morphologically distinct and spatially separate components, one comprising typical well differentiated adenoma malignum and the other a moderately differentiated neoplasm, in keeping with gastric type adenocarcinoma. Both components were positive for HIK1083 and MUC6 and negative for p16, and did not contain human papillomavirus. It is believed that such a composite tumour has not been described in the literature. It is believed that the component of gastric type adenocarcinoma arose through a process of dedifferentiation within adenoma malignum and we provide circumstantial molecular evidence in support of the interpretation that both components may be clonally related in that they displayed an extra copy of chromosome 7. This raises the possibility of a relationship between these two uncommon types of cervical adenocarcinoma, both of which are thought to exhibit gastric differentiation.

An embryonal rhabdomyosarcoma (sarcoma botryoides) of the cervix occurring in a 30-year-old woman is described. In addition to typical areas of the embryonal rhabdomyosarcoma, including cartilaginous elements, the neoplasm was characterised by the presence of foci composed of highly pleomorphic cells. The significance of this finding is uncertain. These foci may represent areas of dedifferentiation in an embryonal rhabdomyosarcoma.

Two cases of lobular breast carcinoma metastatic to an endometrial polyp are described. Both patients had been treated with tamoxifen and presented with abnormal uterine bleeding. Histology of endometrial biopsy in both cases showed typical tamoxifen-associated endometrial polyps with focal subtle stromal infiltration by metastatic lobular breast carcinoma. This was confirmed by positive immunohistochemical staining with cytokeratin epithelial markers. Metastatic breast carcinoma may rarely involve tamoxifen-associated endometrial polyps. Because primary endometrial carcinomas may also arise within tamoxifen polyps, these should be extensively sampled. We briefly review polypoid uterine lesions that may occur secondary to tamoxifen therapy.

Precancerous lesions, often detected by cancer screening programmes, fascinate histopathologists. Microscopic examination shows some of the architectural and cytological features of malignancy but no invasion of surrounding healthy tissue. As a practising histopathologist, I have always felt uncomfortable that patients with these conditions, such as ductal carcinoma in situ of the breast, are often told …

A 60-year-old woman presented with a large painful haemorrhagic ulcer of her left lower abdomen. Her medical history included ulcerative colitis, breast cancer, stroke and atrial fibrillation for which she was on warfarin. On examination she had a 15×6 cm large necrotic haemorrhagic ulcer of the left lower abdomen (figure 1). The border appeared violatious and undermined and the …