Naoya Shimizu

Human parvovirus B19 infection: Immunohistochemical and electron microscopic studies of skin lesions

Erythema infectiosum is known to be caused by human parvovirus B19 and shows characteristic clinical skin manifestations in children, although adult cases of human parvovirus B19 infection do not always show such characteristic features. Recently, we experienced an epidemic adult cases of human parvovirus B19 infection and examined the erythematous skin lesion by immunohistochemistry and electron microscopy to clarify the pathogenesis of the skin manifestations. Light microscopic examination showed slightly irregular‐shaped vessels in the dermis. By immunohistochemistry, using anti‐human parvovirus B19 monoclonal antibody, positive reactions were found in endothelial cells. No immunoglobulins were found, but C3 deposits were present in the perivascular areas. By electron microscopy, virus particles were found in the cytoplasm of endothelial cells. An inflammatory reaction due to the direct human parvovirus B19 infection in dermal vessels seems to be an important factor in the pathogenesis of the skin manifestations.

Histopathogenesis of inflammatory linear verrucose epidermal naevus: histochemistry, immunohistochemistry and ultrastructure

SummarySkin lesions of three patients with inflammatory linear verrucose epidermal naevus (ILVEN) were examined. Histologically, orthokeratosis and parakeratosis were alternately seen in the acanthotic epidermis. By N-(7-dimethylamino-4-methyl-3-coumarinyl)maleimide staining, the horny cells in the parakeratotic epidermis showed a cytoplasmic SH pattern and a weak membranous SS pattern. The orthokeratotic epidermis revealed an increased involucrin expression, whereas the parakeratotic epidermis showed almost no involucrin expression. Ultrastructurally, in the parakeratotic epidermis, the living keratinocytes had prominent Golgi apparatuses and vesicles in the cytoplasm. In the intercellular spaces in the upper spinous layer through to the lower horny layer, an electron dense, homogeneous substance was deposited. The cytoplasm of the horny cells was filled with keratin filaments and contained remnants of nucleus and cytoplasmic membrane structures, and some lipid droplets. The marginal band formation was incomplete. Most of these ultrastructural abnormalities were not found in the orthokeratotic epidermis. There are both similarities and differences in histopathogenesis of the parakeratotic epidermis between ILVEN and psoriasis. A unique finding was the lack of involucrin expression in the ILVEN parakeratotic epidermis.

ANTI‐HAIR KERATIN MONOCLONAL ANTIBODY (HKN‐2)

BALB/c mice were immunized with human hair fibrous proteins. Then their spleen cells were fused with Sp2/0‐Agl4 mouse myeloma cells. Antibody‐producing hybridomas were selected by ELISA method and cloned by limiting dilution. A monoclonal antibody was chosen and designated as HKN‐2. Immunohistochemically, on frozen sections of normal human skin, HKN‐2 was found to recognize the suprabasal cells of epidermis and hair follicle, the cells in the keratogenous zone of hair shaft, the sebaceous cells and the ductal and myoepithelial cells of sweat glands. The basal cells of the epidermis and lower hair follicle, hair matrix cells and secretory cells of sweat glands did not react with HKN‐2. An immunoelectron microscopic method showed that the positive reaction to HKN‐2 was located on the tonofilaments in the cytoplasm. It was concluded that there might be a common antigenic determinant between hair and other skin epithelial tissues. A complexity in keratin manifestation in each epithelial tissue of the skin was suspected.

Immunohistochemical study on keratin expression in certain cutaneous epithelial neoplasms: basal cell carcinoma, pilomatricoma, and seborrheic keratosis

We investigated immunohistochemically 20 basal cell carcinomas (BCC), five pilomatricomas, and nine seborrheic keratoses using anti-BCC keratin monoclonal antibody (BKN-1) and anti-hair keratin monoclonal antibodies (HKN-2, HKN-4∼-7). The neoplastic cells in all the cases of BCC were always uniformly stained by BKN-1, HKN-2, and HKN-4, indicating that the BCC cells display a constant antigenicity of keratin, which may be different from that of the normal epidermis. Although no fluorescence by HKN-6 or HKN-7 was seen in any cases of BCC, HKN-5 partially but strongly stained the neoplastic nests in most cases of BCC; BCC may have differentiation toward the lower part of hair follicular epithelium. In pilomatricoma, all the anti-keratin monoclonal antibodies showed a similar staining pattern; the differentiating neoplastic cells undergoing transition from basaloid to eosinophilic were positively stained by each antibody in all the cases. This finding of pilomatricoma corresponds to that of the differentiating cells in the inner hair layers, especially in the hair cortex. In seborrheic keratoses, no fluorescence was recognized with HKN-5∼-7, which stain the lower follicular cells in the normal human skin. The staining patterns of seborrheic keratosis by BKN-1, HKN-2, and HKN-4 were similar to those of the normal interfollicular epidermis. These anti-keratin monoclonal antibodies seem to be useful for the investigation of the direction of differentiation of skin adnexal neoplasms.

Generalized eruptive histiocytoma: an ultrastructural study.

A case of generalized eruptive histiocytoma (GEH) was evaluated and examined histopathologically and ultrastructurally. A 24‐year‐old male had an episode of high fever and drug‐induced eruption prior to the appearance of multiple skin lesions. Uniform, red to dark‐red papular lesions appeared on his cheeks and then became generalized. The lesions were composed of a massive dermal infiltrate of histiocytes, which had oval nuclei and amphophilic cytoplasm. The cytoplasm contained unique annular structures, myeloid bodies and vacuoles. The specificity of these structures is as yet unknown. Reactive stimulation rather than neoplastic proliferation may be a causative factor in GEH.

Intraepidermal pilar epithelioma: a new dermatopathologic interpretation of a skin tumor.

An intraepidermally developed epithelial cell tumor, forming multiple nests, was examined to identify its cytologic characteristics. Histochemically, the tumor cells contained neither glycogen nor lipid substance. By N-(7-dimethylamino-3-methyl-4-coumarinyl)maleimide staining, the cytoplasm of the tumor cells in the periphery of each nest was rich in SH groups but not in SS linkages, whereas centrally located homogeneous tumor cells contained SS diffusely but no SH. The tumor cells showed no activity of phosphorylase and a weak activity of succinic dehydrogenase. Immunohistochemically, antihair keratin monoclonal antibodies specific for hair cells decorated the tumor cells, but carcinoembryonic antigen staining showed no positivity. Ultrastructurally, the tumor cells underwent a keratinization forming a fingerprint pattern of keratin filaments; however, membrane-coating granules and marginal bands were not formed. These intraepidermal tumor cells may have cytologic natures similar to those of hair cortical cells. The term intraepidermal pilar epithelioma is proposed as a diagnosis for this tumor.

Anti-keratin Monoclonal Antibody against Basal Cell Epithelioma Keratin: BKN-1

A BALB/c mouse was immunized with fibrous proteins (FP) extracted from basal cell epithelioma (BCE) and anti‐keratin monoclonal antibodies were produced by a hybridoma technique with a mouse myeloma cell line. One monoclonal antibody was designated as BKN‐1.