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A 53‐year‐old man presented with a 2‐year history of a painless mass on the right cheek. On physical examination, the lump was a solitary, well‐demarcated, mobile lesion. There was no abnormality in the surrounding skin. Ultrasonography demonstrated a single, cystic, well‐defined, subcutaneous cyst, measuring 20 mm in diameter. Laboratory tests, including sex hormones, were within the normal range. The tumor was resected surgically under local anesthesia. The cyst had a slightly yellow wall and contained clear, watery fluid. The patient had no other medical problems and no history of other skin disease. Histopathologically, the unilocular cyst was lined with two layers of epithelium and was devoid of papillary infolding. The inner layer of the cyst was composed of cuboidal to columnar epithelial cells, most of which demonstrated prominent cilia. The outer layer consisted of polygonal cells that contained clear cytoplasm (Fig. 1). No foci of squamous metaplasia were present and the cyst wall did not contain adnexal structures. The inner layer of the epithelium was positive for periodic acid–Schiff (PAS) stain, but contained no diastase‐resistant granules. Figure 1  Hematoxylin and eosin staining. A unilocular cyst lined with two layers of epithelium (original magnification, × 200) Immunohistochemical staining revealed strong staining in the membrane for epithelial membrane antigen (EMA) and diffuse cytoplasmic reaction to cytokeratin in the epithelial component, but carcinoembryonic antigen (CEA) staining was negative. Staining for α‐smooth muscle actin (αSMA) and S‐100 protein was positive in the outer layer (Fig. 2), suggesting myoepithelial cells. There were no desmin, vimentin, amylase or estrogen receptor‐positive cells in the epithelium. 2 α‐Smooth muscle actin (αSMA) staining was positive in the outer layer (original magnification, × 100)

A case of subcorneal pustular dermatosis (SPD) is reported in a 48-year-old man with a 2-year history of hyperthyroidism (Graves’ disease). SPD has been reported in association with IgA monoclonal gammopathy, but to our knowledge it has not been associated with hyperthyroidism. The coexistence of hyperthyroidism and SPD suggests that immunologic factors may play a role in the pathogenesis of SPD.

Chemotherapy-induced acral erythema (CAE) is an uncommon and distinct reaction seen in patients receiving high-dose chemotherapy. The exact pathogenic mechanisms of this disorder are still unknown. We report a 27-year-old woman who presented with red, swollen and painful macules on both palms, clinically consistent with this disease. Histological examination demonstrated vacuolar degeneration of the basal cell layer and spongiotic blisters in the epidermis, especially in the atrophied eccrine ducts and papillary oedema with mild perivascular infiltration of mononuclear and hypersegmented neutrophils. Immunohistochemistry showed that the infiltrating mononuclear cells were CD3-CD16+CD56+ leucocyte function antigen-1+, possibly natural killer cells. The eccrine ducts expressed HLA-DR and intracellular adhesion molecule-1 (ICAM-1). Our findings suggest that cell-to-cell interaction between NK cells and keratinocytes in the eccrine apparatus may induce CAE and may be involved in the pathogenesis of the skin reaction in our patient and possibly in this disease.

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