Dermoid cyst mimicking hematoma in the posterior fossa.

Intracranial dermoid cysts are usually reported to be associated with long lasting or waxing-waning symptoms. Computer tomography (CT) scans usually depict such neoplasms as well-defined areas of low density. This report is about a case of a dermoid cyst, the acute clinical features and CT hyperdensity of which mimicked a hematoma in the posterior fossa. The association of acute onset with CT hyperdensity makes this case of dermoid cyst very unusual.

Central neurocytoma. A clinico-pathologic study of five cases.

Five cases of central neurocytomas are described. The tumors occurred in relatively young patients (range 14 to 43 years; mean age, 27) with no predilection for sex. All the lesions were located in the anterior portion of the lateral ventricles or in the third ventricle, involving the septum pellicidum or the fornix. Histologically, they were composed of uniform cells with round nuclei and clear cytoplasm resembling oligodendrogliomas or, to a lesser extent, ependymomas. In 4 tumors, protein cell nuclear antigen immunostaining showed a low cell proliferation rate. All cases were positive for neuron-specific enolase. Four of the 5 cases were strongly immunoreactive for synaptophysin. The immunohistochemical data were consistent with neuronal differentiation. Resection was subtotal in 4 cases and total in one. Postoperative radiotherapy was given in only one case. The follow-up revealed a good prognosis: 4 patients were alive and had a long survival (from 2 to 8 years). Only one patient died after 14 months for causes unrelated to the neoplasm. The authors emphasize the importance of immunohistochemistry to recognize this benign intraventricular tumor.

Proliferating cell nuclear antigen expression in central nervous system neoplasms.

Proliferating cell nuclear antigen (PCNA) is a cell-cycle-regulated protein, which can be demonstrated in routinely fixed specimens. Studies on various tissues, cell cultures and neoplasms have shown that PCNA labelling index (LI) correlates with flow cytometry, tritiated thymidine LI, bromodeoxyuridine (BrdU) incorporation and Ki67 LI. PCNA LI may have prognostic value in various neoplasms. The present study concerns PCNA immunostaining in a series of neuroglial tumours. We demonstrate that there is a relation between PCNA LI and histological grade, and between PCNA LI and reported thymidine LI, BrdU LI and Ki67 LI. Pleomorphic xanthoastrocytomas and low-grade astrocytomas had the lowest LI, whereas metastases of small cell lung cancer and medulloblastomas had the highest LI. Glioblastomas sometimes showed a certain degree of intratumoral heterogeneity of distribution of immunostained cells. Intratumoral heterogeneity underscores the critical importance of representative sampling of central nervous system neoplasms for kinetic studies. As expected, PCNA LI are somewhat higher than tritiated thymidine LI, BrdU LI and Ki67 LI because PCNA is a marker of G1, S, G2 and M-phases of the cell cycle and not of S-phase only. In addition, because of its long half-life, PCNA may be detected immunohistochemically in cells that have recently left the cell cycle. The immunohistochemical evaluation of PCNA LI is easy to perform on routinely processed material, allowing retrospective studies. PCNA LI may be a useful tool in grading gliomas. However, its prognostic value must be validated by comparing PCNA LI with the follow-up of the neoplasms, and possibly with the responsiveness to anti-proliferative therapy.

Late malignant recurrence of childhood cerebellar astrocytoma.

Juvenile pilocytic astrocytoma of the cerebellum has a benign course and a good prognosis. We report a case of juvenile cerebellar astrocytoma in a 6-year-old girl that underwent surgical resection of the tumor and had two recurrences, 13 and 35 years after first removal. After surgery the patient did not receive any radiation therapy. The last relapse showed histological features of an anaplastic astrocytoma. Six months later the patient died with a diffuse leptomeningeal dissemination. Late malignant transformation of a benign cerebellar astrocytoma is very rare and it is thought to be favored by postsurgical irradiation. The possible pathogenetic mechanisms of this evolution are discussed. This case and the few others reported in the literature emphasize the risk of an unpredictable outcome with the low-grade cerebellar astrocytomas of childhood.

[A case of Merkel carcinoma with facial localization]. / Un caso di carcinoma di Merkel a localizzazione facciale.

A case of Merkel carcinoma is reported. It concerns a 40-year-old lady, who had first noticed the lesion one year before she came to our observation. The authors point out the rarity of this tumour, whose not distinctive gross appearance (firm, sessile tumour with well circumscribed margins; hyperhemic overlaying skin; slowly increasing volume) may suggest other macroscopic diagnoses such as intradermal nevus or nodular basalioma. The authors also point out the usefulness of a prompt correct clinical diagnosis of this lesion, whose clinical behaviour may be highly aggressive.