A case of anti-laminin γ1 (p200) pemphigoid developed after dipeptidyl peptidase-4 inhibitor administration.

A 73-year-old man with diabetes mellitus was referred to our department for ultraviolet treatment for erythematous skin lesions with itching. On dipeptidyl peptidase-4 inhibitor (DPP-4i) sitagliptin (Januvia®) for diabetes mellitus, the erythematous skin lesions appeared and spread to the whole body. At the initial visit, erythema multiforme-like skin lesions with crusts were observed on the trunk and extremities, and the patient was suspected to have drug eruption. Histopathology demonstrated eosinophilic infiltration in the superficial dermis and inflammatory cell infiltration in the epidermis. Sitagliptin was discontinued, and erythematous lesions improved with oral prednisolone. Thereafter the patient was treated with phototherapy and  betamethasone sodium phosphate infusion for residual prurigo. However, blistering skin lesions appeared 5 months later. Histopathological findings were subepidermal blisters with eosinophilic abscess, and bullous pemphigoid was suspected. CLEIAs for autoantibodies to desmoglein 1 (Dsg1), Dsg3 and BP180 were negative. Direct immunofluorescence showed linear depositions of immunoglobulin G (IgG) and C3 at the epidermal basement membrane zone, and indirect immunofluorescence detected IgG anti-epidermal basement membrane zone antibodies, reacting with the dermal side of 1M NaCl-split normal human skin. IgG antibodies reacted with 200 kDa laminin γ1 (p200) by immunoblotting using dermal extracts. These results indicated that this patient was diagnosed with anti-laminin γ1 (p200) pemphigoid developed after DPP-4i administration. Although reports of DPP-4i-related bullous pemphigoid have accumulated, cases of anti-laminin γ1 (p200) pemphigoid developed after DPP-4i administration are rarely reported.

GATA3-Positive Adnexal Adenocarcinoma: Report of a Confusing Case with a Potential Pitfall of Leading to a Misdiagnosis of Urothelial Carcinoma and a Review of Published Work.

We describe a confusing case of GATA3-positive adnexal adenocarcinoma with a potential pitfall of leading to a misdiagnosis of urothelial carcinoma. A 62-year-old male presented with a subcutaneous nodule on the right lower abdomen around a scar from surgery for urothelial carcinoma in the right urinary tract, which had been resected 8 years previously. Histologically, atypical cells possessing ample cytoplasm and partial intracytoplasmic lumens were densely grouped in the subcutaneous expansive nodule and bilateral inguinal lymph nodes dissected. Decapitation secretion could not be seen. Neoplastic cells were positive for CK7, GATA3, and GCDFP15, and negative for CK5/6, CK20, p63, CD10, PAX8, HER-2, and uroplakin-II. Neoplastic cells in the urothelium and the metastasized lung were positive for CK7, CK5/6, and GATA3, and negative for CK20, p63, GCDFP15, and TTF-1. A variable level of GATA3 expression in malignant tumors with apocrine and eccrine differentiation should be recognized by dermatologists.

In-transit recurrence of Merkel cell carcinoma associated with Bowen's disease: The first reported case successfully treated by avelumab.

A 65-year-old Japanese man presented with a dome-shaped nodule, the base of which was contiguous with a dull brown plaque, on the left leg. After local excision of the cutaneous lesion and left inguinal lymph node dissection, several dermal and subcutaneous nodules developed successively on the left lower extremity. Hematoxylin-eosin staining of the primary cutaneous lesion demonstrated uniform neoplastic cells arranged in a trabecular pattern extending from the dermis to subcutis. Mitotic figures were abundant. Although the overlying epidermis was substantially intact, the Merkel cells had invaded the epidermis, resulting in Pautrier-like microabscesses. The hyperplastic epidermis adjacent to the nodule consisted of abnormally growing atypical keratinocytes. The enlarged left inguinal lymph node and successive secondary nodules contained Merkel cells similar to those in the primary nodule. Immunohistochemically, most tumor cells were positive for CAM5.2, synaptophysin, chromogranin A, CD56 and vimentin. The tumor cells in the left inguinal lymph node were positive for CAM5.2, synaptophysin and cytokeratin 20 but negative for CM2B4, and less than 1% of the cells expressed programmed cell death ligand 1. The patient was treated with avelumab, which showed significant efficacy against the in-transit recurrence. Two months later, all nodules had disappeared completely. We describe a case of in-transit recurrence of Merkel cell carcinoma that was associated histologically with Bowen's disease and was successfully treated with avelumab. Although accumulation of additional cases is needed, avelumab therapy may be a useful treatment for in-transit recurrence of Merkel cell carcinoma.

Malignant solitary fibrous tumor in the subcutis: Report of a rare superficial malignant type and review of published work.

An 82-year-old Japanese man presented with a 90 mm × 80 mm subcutaneous nodule on the left chest, not connected to the pleura, described as hypointense on T1 -weighted magnetic resonance imaging. Histologically, a well-demarcated nodule demonstrated a patternless pattern composed of hemangiopericytoma-like and short storiform patterns from the subcutis into deeper tissue. Antler-like branching blood vessels and keloidal-type collagen bundles were seen. Myxoid change was seen in hypocellular areas. Bizarre cells and multinucleated giant cells could be easily identified. Approximately 5 mitoses per 10 high-power fields could be detected. The majority of proliferating spindle cells were positive for CD34, CD99 and BCL2 expression. Signal transducer and activator of transcription (STAT)6 was strongly expressed in the nuclei. The Ki-67 proliferation index was 60%. We performed wide local excision with a 30-mm margin, along with resection of intercostal muscles, fasciae and periostea. Neither local recurrence nor distant metastases have occurred in 16 months of follow up. The present case is consistent with malignant solitary fibrous tumor in the subcutis histologically mimicking myxofibrosarcoma or undifferentiated pleomorphic sarcoma, definitively diagnosed by immunoexpression of STAT6. We performed a review of the published work and identified six previously reported patients with malignant superficial solitary fibrous tumor to validate the characteristics of this rare type. Four men and two women were included. The sarcomas involved the head area, trunk and thigh. Only one tumor-associated death occurred despite excision and radiotherapy. Complete excision is a possible treatment choice for this tumor type.

Indeterminate dendritic cell neoplasm accompanied by eosinophilic pneumonia successfully treated by systemic steroid therapy: Report of the first case with muscular and parotid involvement and review of published work.

A 34-year-old Japanese man presented with an indolent nodule on the right flank. Computed tomography of the chest and abdomen demonstrated a large nodule measuring 55 mm × 50 mm in the abdominal oblique muscle layer of the right flank, and several small nodules were seen in the muscle layer throughout the body and subcutaneous tissue of the lower abdomen. 18 F-fluorodeoxyglucose-positron emission tomography/computed tomography revealed nodular lesions in the bilateral parotid glands, bilateral cervical lymph nodes and lower lobe of the right lung. Intermittently, ground-glass shadows developed in the bilateral lungs. Histologically, sheet-like nodules in the abdominal oblique muscle layer and parotid gland were composed of large polygonal cells with convoluted nuclei and ample eosinophilic cytoplasm. Several lymphocytes and considerable eosinophils were intermingled. Lung biopsy demonstrated an inflammatory infiltrate of lymphocytes and considerable eosinophils in the alveoli. Immunohistochemically, polygonal cells were positive for S100 protein and CD1a, but negative for langerin and BRAFV600E . Some cells were positive for CD68. Electron microscopy demonstrated histiocytic cells with phagosomes and interdigitating processes. However, no Birbeck granules were observed. Eosinophilia was seen in the peripheral blood. Multifocal nodules and ground-glass shadows gradually diminished following systemic administration of oral prednisolone. We describe a case of indeterminate dendritic cell neoplasm with multifocal involvement of the muscle, subcutis, lymph node and parotid gland accompanied by chronic eosinophilic pneumonia that was successfully treated by systemic steroid therapy. Neither muscular nor parotid indeterminate dendritic cell neoplasms accompanied by eosinophilic pneumonia have been previously reported.