Papillon-Lefèvre syndrome (PLS) is a rare autosomal-recessive genodermatosis characterized by palmoplantar hyperkeratosis and severe early-onset periodontitis. The development of malignant cutaneous neoplasms within the hyperkeratotic lesions of the syndrome is quite rare. Here, we report on a 51-year-old Japanese woman with PLS associated with recurrent malignant melanoma (MM). Mutation analysis of the cathepsin C gene revealed that the proband was homozygous for a missense mutation, c.415G→A, which is predicted to result in the amino acid substitution p.G139R. Including our case, 4 families have been described as having PLS with MM, 3 of which are Japanese, implying a high incidence of melanoma development in Japanese PLS patients. We suggest that hereditary palmoplantar keratoderma (PPK) in Japanese patients might be predisposed to MM. A literature review revealed that in 18 cases of MM-associated PPK, 13 (76%) were Japanese, suggesting a high incidence of MM in Japanese PPK patients. This tendency might be attributable to the high frequency of acral lentiginous melanoma in Japanese subjects, in contrast to a lower frequency of this subtype in Caucasians.

Lichen planus (LP) is a chronic inflammatory disorder involving the skin or mucous membranes. Previous studies have demonstrated that some LP patients showed positive enzyme-linked immunosorbent assay (ELISA) for desmoglein (DSG) antibodies. We report a case with intractable painful oral lesions. ELISA indices for DSG1 and 3 antibodies were increased by 49 and 36, respectively. Histopathological analysis revealed irregular acanthosis and band-like infiltration of lymphocytes at the dermal-epidermal interface. Direct immunofluorescence revealed negative deposits of immunoglobulin G and C3 in intracellular spaces of the epidermis. Indirect immunofluorescence of normal skin also did not detect any antibodies. Consequently, we made a final diagnosis of oral LP. The previous two LP cases with positive ELISA for DSG antibodies and our case manifested the erosive form, the most advanced oral LP. Therefore, it is a possibility that severe damage of keratinocytes may induce generation of DSG antibodies. However, negative results of immunofluorescence and no relation between disease severity and titers of antibodies make the possibility unlikely. We should measure titers of DSG antibodies in LP patients and accumulate data to establish a valid conclusion.

The most life-threatening complication developing in patients with recessive dystrophic epidermolysis bullosa (RDEB) is squamous cell carcinoma (SCC). To improve patient prognosis, early detection of regional lymph node metastasis is required. Herein, we report a patient diagnosed with non-Hallopeau-Siemens RDEB who developed SCC on the left foot with inguinal lymph node swelling. Use of the sentinel node biopsy (SNB) technique favorably minimized defective damage to the inguinal region in this case. Genetic analysis identified one novel COL7A1 mutation, a maternal c.238G > C (p.A80P) and one previously reported mutation, a paternal c.3631C > T (p.Q1211X). A published work review demonstrated that no COL7A1 mutations specific for SCC development in RDEB have previously been identified. It remains unclear if SNB in combination with gene diagnosis is beneficial for the management of SCC in RDEB patients, however, because of the limited number of case reports. To address this issue, COL7A1 mutational analysis should be performed in as many cases of RDEB as possible.

Infection of microbial pathogen triggers the innate immune system, and the induction of interferons (IFNs) play a vital role in host antiviral response. Stimulator of interferon genes (STING) was identified as a crucial regulator of the DNA sensing pathway, and activates both nuclear factor-κB and interferon regulatory factor 3 transcription pathways to evoke IFNs production. In this study, we studied the upregulation of STING mRNA expression, induced by IFN-γ in human keratinocytes (HaCaT). STING promoter assays clarified that a gamma-activated sequence (GAS), located at - 7 to - 15-bp, is required for IFN-γ-upregulated promoter activity. Furthermore, an electrophoretic mobility shift assay showed that signal transducers and activators of transcription 1 (STAT1) attach to the GAS motif on the human STING promoter region. This indicates that IFN-γ/Janus kinases/STAT1 signaling is essential for the STING upregulation in human keratinocytes.

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