Hirokazu Yasuno

Merkel cell carcinoma with partial spontaneous regression: An immunohistochemical, ultrastructural, and TUNEL labeling study

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.

Facilitated wound healing by activation of the Transglutaminase 1 gene.

Transglutaminase 1 (TGase 1) is a Ca(2+)-dependent enzyme which catalyzes epsilon-(gamma-glutamyl)lysine cross-linking of substrate proteins such as involucrin and loricrin to generate the cornified envelope at the cell periphery of the stratum corneum. We have shown that disruption of the TGase 1 gene in mice results in neonatal lethality, absence of the cornified envelope, and impaired skin barrier function. Based on the importance of TGase 1 in epidermal morphogenesis, we have now assessed its role in wound healing. In neonatal mouse skin, TGase 1 mRNA as well as keratin 6alpha was induced in the epidermis at the wound edges as early as 2 hours after injury and that expression continued in the migrating epidermis until completion of re-epithelialization. The TGase 1 enzyme co-localized on the plasma membrane of migrating keratinocytes with involucrin, but not with loricrin, which suggests the premature assembly of the cornified envelope. Similar injuries to TGase 1 knockout mouse skins grafted on athymic nude mice showed substantial delays in wound healing concomitant with sustained K6alpha mRNA induction. From these results, we suggest that activation of the TGase 1gene is essential for facilitated repair of skin injury.

Soluble CD30 is more relevant to disease activity of atopic dermatitis than soluble CD26

It is suggested that CD30 and CD26 are surface molecules expressed on activated Th2 and Th1 cells, respectively. We examined plasma levels of soluble CD26 (sCD26) and sCD30 in patients with atopic dermatitis (AD) when their eruptions were aggravated and in non‐atopic healthy controls, and then analysed the possible correlation between these values and the levels of several clinical markers. The plasma levels of both sCD30 and sCD26 were significantly higher in AD patients than in controls, both in exacerbation status and after conventional treatment. Multiple regression analyses showed that plasma sCD30 was a much better predictor of the levels of serum IgE, serum LDH and plasma sCD25, and the area and the score of AD eruption than sCD26, although elevated levels of both sCD30 and sCD26 are associated with these clinical predictors of AD. Importantly, sCD30 plasma levels decreased significantly in AD patients after conventional treatment, while no significant transition was noted in the concentration of sCD26. Moreover, a significant reduction of sCD30 levels was observed in the group of patients whose eruption score was reduced > 50%, whereas it was not in those < 50%. These findings provide evidence that the successful treatment of AD is associated with down‐activation of Th2.

PUVA-induced lichen planus pemphigoides

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.

Glomeruloid hemangioma in POEMS syndrome shows two different immunophenotypic endothelial cells

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.

Increased levels of serum tissue inhibitor of metalloproteinase‐1 but not metalloproteinase‐3 in atopic dermatitis

Matrix metalloproteinases and their specific inhibitors, tissue inhibitors of metalloproteinases (TIMPs), contribute to inflammation‐induced tissue destruction and subsequent remodeling for maintenance of tissue homeostasis. Since the production of these enzymes and their inhibitors is regulated by mediators such as proinflammatory cytokines and growth factors, elevated levels of serum TIMPs and/or MMPs have been documented in patients with several inflammatory disorders. In this study, we examined the role of TIMPs and MMPs in the pathogenesis of atopic dermatitis (AD) by evaluating the serum levels of TIMP‐1 and MMP‐3 in 40 patients with AD and 20 control subjects by ELISA. The serum TIMP‐1 levels were significantly higher in AD patients in exacerbation status than in nonatopic subjects, whereas serum MMP‐3 levels were not significantly different between them. As a result, AD patients revealed significantly elevated TIMP‐1/MMP‐3 ratios. The levels of serum TIMP‐1 were significantly reduced in AD patients following conventional treatments. Significantly higher values of peripheral eosinophil counts, serum levels of IgE and lactate dehydrogenase, eruption score, and eruption area were noted in the AD patients with elevated TIMP‐1 levels when compared with those with normal values. Moreover, the points of chronic eruptions such as lichenification and prurigo were significantly higher in the patients with elevated TIMP‐1 levels than those with normal TIMP‐1, while those of acute lesions such as oozy/microvesicles and oedema were not different between these groups. Serum TIMP‐1 level may be a useful marker to estimate the long‐term disease activity of AD.

Low incidence of Ha-ras oncogene mutations in human epidermal tumors.

Activation of the Ha-ras oncogene by point mutations has been suggested to play a role in animal skin carcinogenesis models. In this study, we investigated the significance of the Ha-ras mutations in human epidermal tumors. DNAs from paraffin-embedded tissues of benign and malignant human epidermal tumors (27 samples from 25 patients) were prepared and examined for point mutations of codons 12, 13 and 61 of Ha-ras gene by polymerase chain reaction and oligonucleotide hybridization. Only one sample of basal cell carcinoma and one sample of keratoacanthoma were found to carry an A to T transversion at the second position of codon 61. This low incidence of Ha-ras mutations suggests that the mutational activation of the gene may not be primarily involved in human epidermal tumorigenesis.

Molecular cloning of human epidermal transglutaminase cDNA from keratinocytes in culture.

We have isolated a cDNA encoding human epidermal transglutaminase, a key enzyme of terminal differentiation of keratinocytes. A cDNA library from cultured human keratinocytes was screened by a PCR-amplified partial cDNA fragment of the enzyme with oligonucleotide primers based on the homology of the transglutaminase family. The cDNA is 2734 bp coding a protein of 817 amino acids. The several regions including the active site cysteine residue are highly conserved among the transglutaminase family. However, the charged N-terminal domain is unique to the epidermal transglutaminse, suggesting that the region is involved in the function of the enzyme in keratinocytes.

Disseminated Epidermolytic Acanthoma

A 65‐year‐old Japanese male suffered from numerous brownish papules on his back for 6 months. Clinical appearance resembled seborrheic keratosis, but light microscopic examination revealed epidermolytic hyperkeratosis. Electron microscopic findings were the same as those of epider‐molytic hyperkeratosis and systemic nevus verrucosus. It may be concluded that this type of skin disease is an acquired epidermolytic hyperkeratosis.

Immunolocalization of fibroblast growth factor receptors in normal and wounded human skin

Abstract. Fibroblast growth factors (FGFs) have been shown to play diverse roles in various tissues. To define their sites of action in normal human skin and during wound healing, we determined the protein expression of the four known fibroblast growth factor receptors (FGFRs) in normal and wounded human skin by immunohistochemistry. Four receptors (FGFR-1 to FGFR-4) showed distinct patterns of expression in normal skin. Expression of FGFR-1 was widespread in the epidermis, appendages, arrector pili muscles, blood vessels, and dermal fibroblasts. Intense expression of FGFR-2 and FGFR-4 was seen in the arrector pili muscles and smooth muscle cells of vessels. In the epidermis, the basal layer showed immunoreactivity for FGFR-2, whereas the suprabasal layers and the inner layers of hair follicles showed strong immunoreactivity for FGFR-3. In wounded skin, there was strong expression of FGFR-1 and FGFR-3, and moderate expression of FGFR-2 and FGFR-4 in the basal layer in newly forming epidermis. In granulation tissues, neocapillaries expressed all four FGFRs, fibroblasts/myofibroblasts expressed FGFR-1 and FGFR-3, and mononuclear inflammatory cells expressed FGFR-1 and FGFR-3. Our results suggest that the differences in the spatial patterns of FGFR expression in normal skin may generate functional diversity in response to FGFs and that in wounded skin, FGFs may function in wound healing via the induced FGFRs.