A 20-year-old man presented with slowly progressing symptoms indicative of increased intracranial pressure. Two weeks later he underwent surgery for placement of a ventriculoperitoneal shunt. Cytological examination of the patient's cerebrospinal fluid (CSF) revealed atypical cells that contained no detectable melanin deposits, but proved to be immunocytochemically positive for monoclonal antibodies to melanocytic cells (HMB-45) and S-100 protein. Dermatological and ophthalmological examinations failed to demonstrate any abnormalities. On the basis of these findings, a diagnosis of primary leptomeningeal melanoma was made. Gadolinium-enhanced magnetic resonance (MR) images of the brain and spinal regions obtained 2 months after admission demonstrated typical widespread leptomeningeal enhancement. Results of technetium-99m-hexakis (2-methoxyisobutyl isonitrile) single-photon emission computerized tomography (99mTc-MIBI SPECT) scanning revealed intense uptake of the isotope in the leptomeningeal regions and some cisterns. The patient's condition progressively worsened and he died 5 months after admission. The diagnosis was confirmed at autopsy. Immunocytochemical analysis of CSF performed using HMB-45 and S-100 protein antibodies is important for the diagnosis of leptomeningeal melanoma because of the test's simplicity, high specificity, and sensitivity. Gadolinium-enhanced MR imaging is used to demonstrate the extent of the leptomeningeal melanoma. An additional and supplemental neuroimaging modality, 99mTc-MIBI SPECT scanning has good potential for the detection and diagnosis of leptomeningeal melanoma.

A 25-year-old man was admitted to the Department of Neurology, Gunma University Hospital, in June 1997. He had an intellectual disability and had suffered from repeated infection since childhood. Cerebellar ataxia had developed at 19 years of age and he had been clinically diagnosed with ataxia telangiectasia (AT) comprising cerebellar ataxia and oculocutaneous telangiectasia at 24 years of age. He died from pneumonia and renal failure at 26 years of age. Neuropathological examination revealed Purkinje cell loss and atrophy of the dentate nuclei in the cerebellum, anterior horn-cell atrophy and demyelination of the gracile fasciculi in the spinal cord, and the existence of nucleocytomegalic cells in the anterior pituitary gland. These neuropathological findings correlated with previously reported cases of AT. In addition, spongy degeneration was found, predominantly around the blood vessels in the cerebral cortex. Diffuse spongy degeneration and multiple foci of coagulative necrosis with calcification were noted in the white matter. Abnormal vasculature was noted in both degenerative and necrotic areas in the cerebral cortex and in the white matter. The vessels at the center of the areas of spongy degeneration in the cerebral cortex had irregularly arranged and enlarged smooth-muscle-cell nuclei and a distorted, narrow lumen. The vessels present in the white matter were hyalinized. To our knowledge, these vascular abnormalities in the brain parenchyma have not been reported previously.

A case of pigmented squamous cell carcinoma (SCC) with dendritic melanocyte colonization in the external auditory canal is reported and the previous cases are reviewed. A 65-year-old Japanese female was referred with a 7-year history of otitis. The patient also had a darkly pigmented 9 x 8 mm nodule in the external auditory canal. Microscopically, the tumor was SCC, but in some areas melanin pigments were found in the cytoplasm of the tumor cells. The tumor was thus diagnosed as pigmented SCC. As well as the tumor cells, dendritic-shaped cells colonized the tumor parenchyma and were immunohistochemically defined as melanocytes. The authors believe this is the first case of pigmented SCC with dendritic melanocyte colonization in the external auditory canal.

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Rosai-Dorfman disease (RDD) was formerly known as “sinus histiocytosis with massive lymphadenopathy”, and cases involving the gastrointestinal tract are rare. We present a case of pure extranodal RDD, resected as a polypoid lesion in colonoscopic study. The patient was a 62-year old woman with a history of sigmoidectomy for unexplained peritonitis. Microscopic study of the polypoid lesion showed the submucosal mass with histological and immunological features of RDD. The whole body computed tomography revealed neither lymphadenopathy nor tumor-like mass.

We report two cases of "decade survivor" of glioblastoma. Case 1 is a 34-year-old female who developed a tumor in the left frontal pole, and Case 2 is a 46-year-old male with a left frontal tumor. Both tumors were surgically excised and the patients received postoperative chemo-radiotherapy. Histological re-evaluation of the resected tumor tissue confirmed the most malignant type of glioma-glioblastoma. We speculate that the entire extent of tumors had been extirpated by surgery in both cases.

To further clarify the histopathological findings of the floral variant of follicular lymphoma (FVFL), we studied 13 Japanese cases. Two histological subtypes of neoplastic follicles of FVFL have been described: (i) A macrogerminal center pattern where the mantle zone lymphocytes were invaginated into the neoplastic germinal center, often reminiscent of a floral design. (ii) A microgerminal center pattern where the massive invasion of mantle zone lymphocytes resulted in almost complete breakage of the neoplastic follicles. In the former pattern, the neoplastic germinal center usually contained large clusters of tumor cells, whereas in the latter, small clusters of up to 20 tumor cells or isolated tumor cells were observed in the neoplastic germinal centers. Moreover, occasional tumor cells showed a lymphocytic and/or histiocytic Reed-Sternberg cell (L&H cells)-like morphology. Both types of neoplastic follicles were observed to a varying degree in most cases. The macrogerminal center pattern was predominant in nine cases (70%), whilst the microgerminal center pattern was predominant in only four cases (30%). Three lesions (23%) had a marginal zone component. Immunohistochemistry showed that atypical follicular center cells, including L&H cells, were CD3-, CD5-, CD10+, CD20+, CD43-, bcl-2+, cyclinD1-. The overall histological findings of the macrogerminal center are similar to those of florid progressive transformation of germinal center (PTGC), whilst the microgerminal center pattern is similar to that of nodular lymphocyte-predominant Hodgkin lymphoma. Initially, the differential diagnosis between FVFL and florid PTGC was emphasized. However, the present study indicates that nodal marginal zone B-cell lymphoma possessing floral follicles and nodular lymphocyte-predominant Hodgkin lymphoma should be added to the differential diagnosis of FVFL. The germinal center B-cell nature of FVFL is most clearly recognizable by immunohistochemistry, though histological appearance alone may cause some diagnostic problems.