A 55-year-old woman presented with an asymptomatic red plaque on the left upper back for 6 or 7 years. The lesion was depressed in response to finger pressure. The clinical diagnosis was anetoderma. Histopathologically, the characteristic cells of cellular dermatofibroma proliferated within the thinned dermis, which showed atrophy of about 60 or 70%. The proliferated cells were positive for factor XIIIa and negative for CD34. The involved dermis showed the loss of elastic fibers on elastica van Gieson stain. Electron microscopically, the proliferating cells phagocytized the elastic fibers. We report a typical case of atrophic dermatofibroma and show the possibility that the cause of this disease might be elastophagocytosis between the collagen fibers by the dermatofibroma cells.

Primary cutaneous signet ring cell carcinoma (PCSRCC) is a very unusual but distinctive clinicopathologic entity that can simulate metastatic adenocarcinomas. It is defined as a diffuse malignant epithelial neoplasia localized in the dermis and subcutis without epidermal involvement, showing variable amounts of signet ring cells, without evidence of visceral adenocarcinoma. We present 2 cases of PCSRCC, which involved eyelids and axilla respectively. Despite thorough systemic workup, primary sources could not be demonstrated in either case. The tumor cells are positive for gross cystic disease fluid protein 15 in addition to a variety of glandular markers. Furthermore, both cases were immunostained with cytokeratin 20 (CK20). In conclusion, we report 2 cases of PCSRCC expressing CK20 immunoreactivity. CK20-positive primary cutaneous tumors should include PCSRCC in addition to Merkel cell carcinoma.

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Summary We describe two patients with BRAF‐mutated melanoma of the epithelioid cell type arising from primary acquired melanosis with severe atypia of the right bulbar conjunctiva. Patient 1 was a 71‐year‐old Japanese man. After adjuvant cryotherapy and enucleation of the right eyeball, therapy with vemurafenib was administered for a distant metastasis to a lumbar vertebra, accompanied by erythema multiforme and two keratinous tumours. The patient died due to metastases to the liver and multiple vertebrae, despite therapy with nivolumab and combination therapy with dabrafenib plus trametinib. Patient 2 was a 72‐year‐old Japanese man. After adjuvant cryotherapy, periodic mitomycin C eye drops, and excision of the superficial portion of the right parotid gland and the dissection of cervical lymph nodes, he was treated with adjuvant combination therapy with dabrafenib plus trametinib. Dermatologists should be familiar with BRAF‐mutated conjunctival melanoma, which is usually located on the bulbar conjunctiva and associated with more frequent distant metastasis.

This is a unique case for two following reasons: 1) the first biopsy revealed non-specific findings compatible with erythema nodosum; and 2) before the treatment, the nodules regressed spontaneously. Dermatologists should take multiple skin biopsies for EN lesions with the non-specific histopathological findings not to refute the existence of this disease.

Erythema multiforme is a relatively common skin disorder; the most common cause is herpes simplex infection, but topical sensitivities reportedly also provoke this reaction. We report here a case that progressed to toxic epidermal necrolysis due to contact with ultraviolet (UV)-cured inks. The diagnosis was confirmed by patch tests to acrylates in the UV-cured inks, histopathological studies of the lesions, and positive patch test to 1,6-hexanediol diacrylate.

A 68-year-old Japanese man presented with a nodule that had been present for 5 to 6 years on the right side of the back. Physical examination revealed a dome-shaped, 12 x 13-mm, dark red nodule. It was excised with a 2 to 3-mm margin. The patient remained free of disease during 77 months of follow-up. Microscopic examination revealed a bulb-like tumor in the dermis, contiguous with the overlying epidermis. It was composed of small, monomorphous, cigar-shaped basaloid cells in linear, parallel rows, resembling the palisading of nuclei of Verocay bodies, and presenting a rippled-pattern. There were scattered cells showing sebaceous differentiation with vacuolated cytoplasm and scalloped nuclei. There were tiny, duct-like spaces. The tumor revealed characteristics of rippled-pattern sebaceoma. The present case is the first reported rippled-pattern sebaceous neoplasm on the back. Many spindle cell tumors, such as basal cell carcinoma, pleomorphic adenoma, dermatofibrosarcoma protuberans, myofibroblastoma, and leiomyoblastoma, in addition to trichoblastoma and sebaceoma, can have a rippled-pattern.

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