Skin samples from patients with extra-mammary Paget disease, Bowen's disease, atopic dermatitis, psoriasis and non-lesional skin of nevus pigmentosus were immunohistochemically examined with an anti-soluble erythropoietin receptor antibody (anti-sEPOR antibody), and only the dermal mast cells positively stained in all skin samples were examined. These positively stained dermal cells were proved to be mast cells by double staining with anti-sEPOR antibody and either with anti-bikunin antibody or anti-tryptase antibody. Immunoelectron microscopically these EPOR were found in the secretory granules of the dermal mast cells. Further, EPOR in the mast cells may be consisting of only the extracellular domain of erythropoietin receptor molecule as the mast cells were immunohistochemically not reacted with an antibody to the C-terminal peptide of EPOR. Human mast cell line, HMC-1 cells has immunohistochemically the erythropoietin receptor, which was consisting of a 43 kDa major protein and a 20 kDa minor protein in the immunoelectrophoresis. These data may indicate that EPOR in the mast cells may not be the whole molecule, but probably the soluble one of EPOR.

Angiosarcoma of the face and scalp of the elderly frequently recurs locally, metastasizes early despite various treatments, and has a poor prognosis. We describe a patient who had angiosarcoma of the scalp with pulmonary metastasis. Local recurrence occurred after excision and local and arterial administration of IL‐2. A weekly administration method of docetaxel was therefore selected, resulting in complete remission of the pulmonary metastasis and a partial response of the local recurrence. This favorable clinical outcome in our case suggests that docetaxel therapy may be an option for the treatment of angiosarcoma of the scalp with pulmonary metastasis.

Myoepithelioma originates almost exclusively from myoepithelial cells of the salivary, prostate and mammary glands. The skin is a very rare site where myoepithelioma occurs. We describe a patient with a myoepithelioma on the right cheek seen as a subcutaneous nodule that was separated from the parotid gland at surgical resection. Histopathological findings were consistent with those of a myoepithelioma that had originated from the parotid gland, suggesting that this tumor may have developed from the accessory parotid gland.

Human mast cells are well known to produce a serine protease, tryptase, which appears to play a pathogenic role in various skin inflammations. It was previously reported that a rat homologue of bikunin may inhibit tryptase activity. Various type of cells (i.e. keratinocytes) are able to produce this protein inhibitor, it still remains unclear if bikunin is present in dermal inflammatory milieu, in which mast cells, through secretion of tryptase, play an inflammatory role. Therefore, the purpose of the present study was to exploit expression and production of bikunin in dermis and dermal constituents. We first compared the dermal mast cells in psoriatic lesions with those in lesional skin of atopic dermatitis or of chronic eczema by use of immunoelectron microscopy and immunohistochemical analyses using antibodies to bikunin and tryptase. Then, we tested what kinds of cytokines may regulate the de novo synthesis of bikunin. To do so, RNA was extracted from a human mastocytic cell line, HMC-1, reverse-transcribed, and semiquantitative RT-PCR was performed using primers specific for bikunin. With immunoelectron microscopy, bikunin was found to localize on the cell membrane, while tryptase was in the secretary granules of the mast cells. In psoriatic lesions, around 70% of dermal mast cells were positive for both tryptase and bikunin, and the remaining was mostly positive for tryptase, but the expression of bikunin was under the detection limit of the experimental setting. This observation was seen in only psoriatic lesions, even in almost cured lesions, while in atopic dermatitis or chronic eczema only mast cells doubly positive for bikunin and tryptase were seen. In HMC-1, bikunin was constitutively expressed at an mRNA level, which was upregulated by stimulation with interleukine-4, but was suppressed by interferon-gamma. Bearing in mind the concept that in psoriasis local cytokine milieu is shifted toward a Th1 pattern (predominant secretion of interferon-gamma), tryptase-positive, bikunin-negative mast cells may be induced.

An infant skin disease with clusters of nodules in the diaper contact area was reported as granuloma gluteale infantum. Recently, the number of elderly patients with this condition has increased, and it has been reported as diaper-area granuloma of the aged. These lesions are presumably caused by irritation from feces and urine. We observed similar cutaneous symptoms in six elderly patients, five of whom revealed clusters of nodules arranged in a circular pattern in the gluteal region presenting a peculiar clinical picture. They were all bedridden and wore cloth diapers. We speculate that wearing a cloth diaper seems to be a major factor behind this condition. Another factor was sitting during the day. A subject had lesions with nodules on the scrotum. The distribution of nodules appeared to be related to the body position and vigorous movement of the patient. In all cases, topical steroid therapies were not effective. They were all positive for bacteriuria. Chronic urinary tract infection further irritates the skin. It is necessary to reduce urine contact and keep the lesion clean.