Satoru Shinkuma

Type VII collagen (COL7), a major component of anchoring fibrils, is essential for dermal‐epidermal adhesion and pathogenic variants in COL7A1 , encoding COL7, cause dystrophic epidermolysis bullosa (DEB). In normal skin, COL7 is localised just beneath the lamina densa. In contrast, previous immunoelectron microscopy (IEM) studies of DEB skin with residual COL7 expression demonstrated aberrant localisation of COL7 above the lamina densa and hemidesmosomes of epidermal basal keratinocytes, possibly reflecting impaired secretion of defective COL7. However, conventional microscopy techniques lack sufficient spatial resolution to clearly visualise individual protein distributions and resolve this finding. Here, we revisit the abnormal localisation of COL7 using two higher‐resolution approaches: structured illumination microscopy (SIM) and expansion microscopy (ExM). In normal human skin, the COL7 NC1 domain colocalised with type IV collagen (COL4), a surrogate marker of the lamina densa and was consistently detected beneath integrin α6 (ITGA6), a hemidesmosomal marker. In DEB skin with residual COL7 expression, COL7 was detected above ITGA6 within basal keratinocytes, recapitulating previous IEM observations. SIM quantitatively confirmed significant BMZ disorganisation in DEB, whereas ExM showed a consistent but non‐significant trend, likely due to variability in expansion factors. These findings demonstrate that high‐resolution fluorescence imaging can reproduce classic IEM observations of COL7 mislocalisation, suggesting its potential as a more accessible complementary approach for morphologic assessment of DEB.

We describe the case of a man with porokeratosis in whom somatic FDFT1 splice-site mutations and promoter hypermethylation contributed to disease development. The phenotypic diversity associated with FDFT1 alterations provides novel insight into the molecular pathogenesis of porokeratosis.

This manuscript presents a detailed case study of familial instances of pseudoxanthoma elasticum (PXE)-like syndrome, focusing on the elevation of protein induced by vitamin K absence or antagonist (PIVKA)-II as a potential biomarker. Our findings suggest that PIVKA-II may serve as a sensitive marker for the pathophysiology of PXE-like syndrome, and we propose that vitamin K supplementation could be beneficial in managing this disorder.

The histopathologic diagnosis of poorly differentiated cutaneous angiosarcoma can be challenging. We report a case of cutaneous epithelioid angiosarcoma with numerous multinucleated giant cells (MGCs) developing pulmonary metastasis. A 79-year-old man presented with a red-purple plaque on the scalp. A skin biopsy revealed epithelioid cell proliferation, admixed with numerous MGCs, and background hemorrhage. Vascular spaces were focally present and lined by atypical endothelial cells, including MGCs. Immunohistochemically, tumor cells, including MGCs, were positive for CD31, D2-40, and ERG. The patient received radiation therapy and chemotherapy, after which a follow-up CT scan revealed symptomless pneumothorax and pulmonary metastases. The patient received palliative partial lung resection, and the specimen revealed histopathological and immunohistochemical features similar to the primary cutaneous lesion. Our report expands the morphologic spectrum of cutaneous epithelioid angiosarcoma. Cutaneous angiosarcoma is an aggressive neoplasm; thus, awareness of this rare manifestation is important.

Our patient with Papillon–Lefèvre syndrome with a novel p.G430V and recurrent p.G301S missense mutation showing aggravation of skin lesions in wintertime. A temperature-dependent cathepsin C enzymatic activity study indicates a possible association between seasonal fluctuations, minimal dental involvement and temperature.

Linear and whorled nevoid hypermelanosis (LWNH) is characterized by hyperpigmentation following Blaschko’s line which usually occurs in infancy o | POSTER