Hemangiopericytoma-solitary fibrous tumour of soft tissue: description of a case showing atypical histological features.

Extrathoracic solitary fibrous tumours have been reported in almost all anatomic sites, but reports of tumours in the extremities or in intramuscular locations, as well as of tumours with atypical histological features and malignant behaviour, are rare. Herein the authors describe a case of hemangiopericytoma-solitary fibrous tumour that arose in the gluteal region of a 47-year-old woman. The tumour showed atypical histological features, such as high cellularity, increased mitotic activity and focal expression of cytokeratins.

Histological and immunohistochemical studies on flower induction in the olive tree (Olea europaea L.).

The aim of this research was to study flower bud differentiation processes in two oil olive cultivars from Tuscan germplasm (Leccino and Puntino). The effect of fruit-set was studied using 'ON' (with fruits) and 'OFF' (without fruits) shoots. Axillary buds were periodically collected at different phenological stages, from endocarp sclerification (July) until budbreak in the following spring. Thin sections were analysed using histology (apex size), histochemistry (RNA, starch and soluble carbohydrates) and cytokinin immunocytochemistry (zeatin localisation). The micromorphological observations and histochemical procedures did not allow us to distinguish axillary buds sampled from 'ON' and 'OFF' shoots. Cytokinin immunocytochemistry revealed early different localisation patterns between 'ON' and 'OFF' samples. Zeatin accumulated only in 'OFF' axillary bud meristems, particularly in July, when endocarp sclerification of fruits from the previous flowering is taking place. At this time, a strong RNA signal was also observed. Both these signals were correlated with floral evocation, and their coincidence with a phenological stage of development provided a useful tool to determine the time when axillary buds switch from the vegetative to the reproductive phase.

Large-cell medulloblastomas. A distinct variant with highly aggressive behavior.

We present four cases of infantile cerebellar neoplasms composed of cells with large vesicular nuclei with prominent nucleoli. All four cases were strongly immunoreactive for synaptophysin, and one case showed immunoreactivity for neurofilaments. Filter hybridization for N-myc and c-myc oncogenes showed a 27-fold c-myc amplification in one case. The cytogenetic analysis in this case showed Double-Minutes and isochromosome 17q. An intracerebral xenograft in nude mice obtained from one such tumor showed a similar morphology to that of the original tumor as well as strong immunoreactivity for synaptophysin and neurofilaments. All the neoplasms were characterized by highly aggressive behavior leading to early cerebrospinal fluid dissemination despite radiotherapy and chemotherapy. We conclude that large-cell medulloblastoma represents a distinct and more aggressive variant of medulloblastoma that requires more aggressive therapy.

Tubular adenoma of choroid plexus: a case report.

A case of choroid plexus neoplasm histologically composed of tubular structures lined by a layer of cuboidal epithelium is reported. The neoplasm was located in the fourth ventricle of a 26-year-old man. The intense positivity for antisera anti-vimentin, anti-cytokeratin, anti-EMA and anti-S100 protein exhibited by these cells was consistent with choroid plexus origin. The patient is alive and in good health 5 years after surgery. The lesion represents a benign choroid plexus neoplasm not previously reported. The name "tubular adenoma of choroid plexus" is suggested for this variant.

N-myc and c-myc oncogenes amplification in medulloblastomas. Evidence of particularly aggressive behavior of a tumor with c-myc amplification.

N-myc and c-myc amplification was investigated in 27 medulloblastomas. DNA was extracted from 19 formalin fixed and paraffin embedded tumors and from fresh frozen tumor tissue in 8 other cases. The results showed no evidence of amplification of N-myc oncogene and only 1 case had a 27 fold amplification of c-myc. Cytogenetically, this neoplasm presented numerous double minute chromosomes (DMs). Moreover, it had an unusual rapidly aggressive course with massive cerebrospinal fluid dissemination unresponsive to intrathecal chemotherapy. Our results indicate a low incidence of N-myc and c-myc gene amplification in medulloblastomas, suggesting that the oncogenic mechanism in these neoplasms is not closely related to DNA gene amplification. C-myc amplification, although not frequently observed, may however provide a growth advantage for medulloblastoma cells in vivo, favoring their rapid dissemination. Medulloblastomas with c-myc activation may represent a subgroup of tumors with a more aggressive behavior.