A 72-year-old woman had suffered from parapsoriasis en plaque (large plaque type) controlled by topically applied psoralen ultraviolet A (PUVA) therapy. The parapsoriasis lesions gradually disappeared, but numerous tiny red papules with pruritus appeared over the forearms and lower legs 120 days after starting PUVA therapy. These papules developed to form violaceous plaques. Histological findings demonstrated the characteristics of lichen planus. Two months later, tense bullae developed on the plaques and on uninvolved skin of the limbs. These were subepidermal, with linear deposits of IgG and C3 along the basement membrane zone (BMZ) in immunofluorescence of peribullous skin, and immunodeposits of type IV collagen along the floor of the bullae. We therefore, diagnosed lichen planus pemphigoides (LPP). Using systemic and topical steroid therapy, the lesions rapidly resolved and there has been no recurrence. This case suggests that the combination of basal cell injuries caused by chronic inflammation and PUVA therapy could expose BMZ components to autoreactive lymphocytes and induce LPP.

We report a case of Merkel cell carcinoma that partially regressed after biopsy. A 76-year-old woman presented with an 1 month history of a rapidly enlarging nodule on her left cheek. After biopsy, the nodule reduced to almost half the size and was excised 1 month later. The excised specimen showed a dense cluster of lymphocytes and fibrosis around the tumor nests. In addition, lymphocytes showed apposition with tumor cells. An immunohistologically dense, even infiltration of CD4+ and CD8+ cells was found around the tumor nests, and more CD8+ cells than CD4+ cells were seen in the tumor nests. By electron microscopy (EM), apoptosis of tumor cells and lymphocytes was observed. Many apoptotic cells were also detected by in situ nick end-labeling (TUNEL) of DNA-breaks, especially in the marginal area of tumor nests surrounded by dense lymphocytic infiltrates. It seems likely that T-cell immunity, which induces apoptosis of tumor cells, may have been involved in tumor regression.

Apoptosis and the expression of p53 protein, an apoptosis-related protein, in the process of healing of a full-thickness burn wound in guinea-pig skin were studied with the terminal deoxynucleotide transferase nick-end labelling method, electron microscopy, and immunohistochemistry, respectively. Apoptosis was detected in the peripheral zone of heat-injured skin from 12 h until day 10 after the burn, with the peak occurring on day 2. The peripheral zone of heat-injured skin showed p53 protein from 12 h through day 2, with the peak occurring on day 2. Apoptosis was also detected in tissues regenerated for covering skin defects. The peak of apoptosis in the regenerated epidermis occurred at days 7-10, when the epidermis was most acanthotic. p53 protein reactivity was also detected in the acanthotic regenerated epidermis, with a peak on day 7. The peak of apoptosis in the granulation and scar tissue took place from day 10 to 14, when the granulation tissue started diminishing, but p53 protein reactivity was not detected there. These findings suggest that apoptosis plays an important part in the elimination of dying and/or dead cells resulting from heat stress, the terminal differentiation of the regenerated epidermis, and the decrease in cellularity during remodelling. The apoptotic process during remodelling may be mediated by some p53-independent pathway.

The case of a Japanese woman with glomeruloid hemangioma, an initial marker for POEMS syndrome, is reported. Her cutaneous lesions were multiple and consisted of glomeruloid hemangiomas, cherry-type capillary hemangiomas, and a mixture of both. The specimens of glomeruloid hemangiomas were studied by paraffin section immunohistochemistry with a large panel of antibodies and electron microscopy, respectively. The lesions, whose size ranged from minute foci to large nodules, were composed of anastomosing vascular channels resembling renal glomeruli and had irregular lumina, often featuring capillaries and sinusoid-like spaces. The vascular channels were lined by a single layer of endothelial cells, which showed two types of cells. The capillary-type endothelium possessed large vesicular nuclei with open chromatin and large amount of cytoplasm. The sinusoidal endothelium possessed small basal nuclei with dense chromatin as well as scant amount of cytoplasm. The former cells had a characteristic CD31+/CD34+/UEA I+/CD68- phenotype. Some of these cells ultrastructurally showed intracytoplasmic lumen formation. The latter cells had a characteristic CD31+/CD34-/UEA I-/CD68+ phenotype. The present study shows that glomeruloid hemangioma has unique morphologic and immunologic features that differ from the traditional hemangiomas as well as littoral cell angioma of the spleen.

We report the clinical, light microscopic, immunohistochemical and ultrastructural features of a verruciform xanthoma that developed in association with a vulval fibroepithelial polyp. To our knowledge, this is the first time that this association has been reported. Immunohistochemical findings confirmed that the xanthoma cells were of a monocyte/macrophage lineage. In addition to typical histological characteristics, prominent vascular ectasias were detected in the deep dermis at the periphery of this lesion. The ectasias may play a part in pathogenesis.