Shuhei Shimao

Acquired tufted angioma showing spontaneous regression

We report a 62‐year‐old woman with acquired tufted angioma. Several scattered reddish nodules were present on the neck and upper chest. During a follow‐up period of 6 months, some of the lesions showed transient spontaneous regression and one disappeared completely. Electron microscopy revealed that a few tumour cells contained Weibel‐Palade bodies in their cytoplasm.

Lichen sclerosus et atrophicus. A histological, immunohistochemical and electron microscopic study

We studied three cases of genital lichen sclerosus et atrophicus (LSA) using histological, immunohistochemical and ultrastructural techniques to elucidate the characteristics of the collagen fibres, the elastic fibres and the interfilamentous matrix in the upper dermal homogeneous zone. In the early stages of LSA, the homogeneous zone caused elaunin fibres to push downwards and partially disappear, the collagen fibres were presumably phagocytosed by fibroblasts, and there were peculiar cells containing numerous vacuoles in the cytoplasm. In the advanced stages of LSA, the homogeneous zones showed newly formed collagen fibres and amorphous, dispersed, medium electron-dense substances that were probably composed of elastin or elastin-like substances and microfilaments originating from the collagen fibres. Immunohistochemically, there were numerous anti-aortic alpha-elastin-positive substances, but there was no positivity for anti-amyloid P component. These findings suggest that in advanced LSA a hybrid substance (elastocollagenous mass) between collagen fibres and elastic fibres may be formed in the homogeneous zone.

Cutaneous focal mucinosis

A 39‐year‐old man had typical cutaneous focal mucinosis on the left forearm. The fibroblasts in the myxomatous lesion had many cytoplasmic vesicles, and on electron microscopy, these were compatible with condensing vacuoles or secretory granules. The fibroblasts in this case were considered to be mucoblasts involved in the over‐production of the ground substance, that was mainly composed of hyaluronic acid.

Microcystic Adnexal Carcinoma

We present a patient with microcystic adnexal carcinoma. The lesion was an indurated plaque on the skin of the right upper lip of a 58-year-old woman which was slowly growing during 27 years. Carcinoembryonic antigen was immunoreactive in the luminal contents of the tumor ducts and in the cytoplasm of cells surrounding ducts. S-100 protein was positive in the cytoplasm of a few cells at the lower dermis. These observations suggested that this tumor was related to sweat glands. Furthermore, electron microscopy revealed that tumor cells had features of eccrine ductal cells. These observations confirm that this tumor appeared at least capable of eccrine duct differentiation.

Primary Cutaneous Meningioma on the Scalp: Report of Two Siblings

Primary cutaneous meningioma (PCM) is a rare tumor whose pathogenesis is quite obscure. We reported PCMs occurring on almost the same occipital region of two siblings studied by histology, immunohistochemistry, and electron microscopy. Both lesions were attached to duras, but extracranial. One lesion was histologically diagnosed as meningothelial meningioma; its tumor cells showed electron microscopically interdigitating cytoplasmic processes with junctional complexes. The other was interpreted as fibroblastic meningioma; its tumor cells were arranged linearly in a stepping‐stone arrangement and had small dense bodies in the cytoplasm. The tumor cells stained positively with anti‐vimentin antibody. Both lesions had adenomatous hyperplasia of the eccrine glands. Although the histologic and electron microscopic features of these two lesions slightly differed from each other, their pathogenesis was essentially considered to be acoelic or rudimentary meningocele.

Expression of schwann cell characteristics in pigmented nevus. Immunohistochemical study using monoclonal antibody to schwann cell associated antigen

A monoclonal antibody to the Schwann cell associated antigen (AHMY1) and a monoclonal antibody to neurofilament proteins (NFP) (AHNF1) each were produced. Using AHMY1, AHMF1, and anti‐S‐100 antibody, 90 pigmented nevi were examined immunohistochemically to clarify the relationship between nevus cells and Schwann cells. All nevus cells had S‐100 protein, but did not have neurofilament proteins. The nevic corpuscle and Type C nevus cell were positively stained with AHMY1 indicating the presence of the Schwann cell associated antigen, while Type A and B nevus cells were entirely negative. This suggests that the nevic corpuscle and Type C nevus cell are closely related to the Schwann cell and differ from Type A and B nevus cells in their development.

Linear Sebaceous Nevus Syndrome

A boy with linear sebaceous nevus syndrome was followed up to 3 years of age, at which time he died of pneumonia. The lesions of nevus sebaceus were located in the midline and on both sides of the face, and there were partial colobomata of the right outer canthus continuous with pseudopterygium and of the left upper eyelid. At 2 months of age, the patient developed infantile spasms. At 1 year, electroencephalography revealed hypsarrhythmia, and left carotid angiography showed an arteriovenous malformation. At 2 years, the mental retardation and delayed motor development were detected.

A case of T-cell lymphoma associated with panniculitis, progressive pancytopenia and hyperbilirubinaemia

A 57‐year‐old woman with T‐cell lymphoma developed subcutaneous tumours and panniculitis and also a progressive pancytopenia.

The local recurrence of pigmented Spitz nevus after removal

A seventeen‐month‐old female had a pigmented nodule on her left lower leg. The excised lesion was histologically diagnosed as a Spitz nevus, composed mainly of spindle‐shaped melanocytes containing large amounts of melanin pigment. When nodular regrowth was seen at the operative site, the recurrent lesion was radically excised as nodular melanoma. However the histological characteristics of the second excised specimen were essentially the same as those in the initially excised one except for the existence of the newly formed collagen fibers, which may suggest an involuting stage in the central portion of the lesion.

Malignant transformation of lymphadenosis benigna cutis : A possibly transformed case and B-cell lymphoma

This study presents a patient who had had a 10 year history of lymphadenosis benigna cutis (LABC) before malignant lymphoma of the skin subsequently developed. During the LABC stage, the lesion showed several foci of cavernous hemangioma‐like nodules which disappeared spontaneously but reccurred repeatedly. These cutaneous nodules were finally diagnosed as malignant lymphoma of the skin with a histology of diffuse, mixed small and large cell type according to the classification of the Working Formulation. Among the subpopulations of tumor cells, B‐cells were highly predominant. It is suggested that LABC may have the potential to transform into malignant lymphoma (probably B‐cell lymphoma).