Palmoplantar keratodermas (PPKs) are a group of disorders that are diagnostically and therapeutically problematic in dermatogenetics1-3. Punctate PPKs are characterized by circumscribed hyperkeratotic lesions on palms and soles with considerable heterogeneity. In 18 families with autosomal dominant punctate PPK (OMIM #148600), we report heterozygous loss-of-function mutations in AAGAB, encoding alpha- and gamma-adaptin binding protein p34, at a previously linked locus on 15q22. p34, a cytosolic protein with a Rab-like GTPase domain, was shown to bind both clathrin adaptor protein complexes, indicative of a role in membrane traffic. Ultrastucturally, lesional epidermis showed abnormalities in intracellular vesicle biology. Immunohistochemistry showed hyperproliferation within the punctate lesions. Knockdown of p34 in keratinocytes led to increased cell division, which was linked to greatly increased epidermal growth factor receptor (EGFR) protein expression and tyrosine phosphorylation. We hypothesize that p34 deficiency may impair endocytic recycling of growth factor receptors such as EGFR, leading to increased signaling and proliferation.

To our knowledge, this is the first case of beta-mannosidosis reported in Japan and the second report in which a gene mutation is identified. The biological importance of beta-mannose moieties in glycoproteins in basal keratinocytes is suggested.

We report a case of erythema elevatum diutinum (EED) in association with malignant B-cell lymphoma. A 62-year-old man developed EED with an unusual distribution involving the palms, soles and nails. Treatment with dapsone was effective for his skin and nails until he developed generalized lymphadenopathy which turned out to be malignant lymphoma. Many haematological diseases, e.g. IgA paraproteinaemia and myeloma, have been reported in association with EED, but not malignant lymphoma. Even though it may just be a coincidence, we would like to add malignant lymphoma as one of the diseases associated with EED because the activity of EED and malignant lymphoma fluctuated in parallel.

Eccrine porocarcinoma is a rare cutaneous neoplasm that mainly affects elderly people and grows slowly over a long period of time but often experiences an accelerated growth phase. Eccrine porocarcinoma may arise de novo or evolve from a pre-existing benign eccrine poroma. We reported a 86-year-old Japanese woman presenting with two reddish-colored pendulated lesions on a keratotic light brown plaque on the right thigh. Dermoscopic examination of the light-brown plaque demonstrated many whitish globular structures in a light-brown background. At the two reddish-colored pendulated lesions, polymorphous and prominent vessel proliferation was observed together with irregularly shaped whitish negative network. Immunohistochemical study demonstrated a positive CEA staining at ductal structures and atypical clear cells of reddish nodules. A diagnosis of eccrine porocarcinoma arising in a pigmented hidroacanthoma simplex was eventually established, and the dermoscopic features of eccrine porocarcinoma from hidroacanthoma simplex was described for the first time.

Thymoma-associated multi-organ autoimmunity disease (TAMA) is a rare paraneoplastic disorder, clinicopathologically similar to graft-versus-host disease (GVHD). Many reported cases follow a difficult course; half of them die from serious infectious diseases subsequent to immunosuppression induced by chemotherapy for unresectable thymoma, or intensive therapies including systemic steroids for complicating autoimmune diseases and GVHD-like symptoms. We report a patient whose skin symptoms were improved subsequently to total thymectomy. The patient also presented with hypogammaglobulinemia, which led to the diagnosis of complicated Good syndrome. Taking account of her immunodeficient condition, antibiotics and i.v. immunoglobulin were administrated promptly on onset of bacterial pneumonia, which was successfully treated. According to a review of the published work, treatments with systemic steroids for skin symptoms have limited effects and may contribute to serious infection. Our case indicates that successful treatment of thymoma itself may lead to the amelioration of the disease. The management priority should be given to the treatment of thymoma and the control of subsequent immune abnormality other than GVHD-like erythroderma.