The significant antiproliferative effect of octreotide seems to be related to the higher expression of sst(5) and the negligible antihormonal effect to the lower expression of sst(2). However, activation of multiple receptors by new analogs may produce better control of tumor cell activities. The dissociation between antisecretive and antiproliferative effects observed in vivo and in vitro confirms that SSAs may induce tumor shrinkage despite the lack of effect on GH secretion.

Herein we report a rare case of a pituitary metastasis from a neuroendocrine tumour mimicking an adenoma. Moreover, starting from this unusual case, the relevant literature concerning the diagnosis and management of patients with metastasis at pituitary level is reviewed. A 69-year-old woman was admitted to our Unit for severe headache, diplopia, and critical visual field impairment. MRI showed a large pituitary mass compressing the optic chiasm and infiltrating the cavernous sinus. Trans-sphenoidal biopsy revealed a pituitary metastasis from a neuroendocrine tumour, in line with the multiple liver lesions that were already considered metastases from an ileal primary neuroendocrine tumour. In vitro receptor characterisation of both pituitary and liver tissues by immunohistochemistry showed a heterogeneous somatostatin receptor subtype pattern, with a predominant expression of sst(2) within the pituitary lesion. However, the liver metastasis receptor profile was completely different from the pituitary. Octreotide LAR was administered first, followed by receptor radiometabolic therapy with radiolabelled somatostatin analogues ((90)Y-DOTATOC and (177)Lu-DOTATATE). After 16 months, MRI showed a significant shrinkage of the sellar mass. Moreover, disappearance of diplopia and visual defects, together with a considerable improvement in quality of life were gradually recorded. To our knowledge, this is the first case of combined treatment using "cold" and radiolabelled octreotide in a pituitary metastasis from a neuroendocrine tumour.

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Summary Microcystic/reticular (MRV) schwannoma has been described since 2008, but remains a rarely encountered entity. MRV has a predilection for visceral locations and has variable histologic appareances. Given its rarity and anatomic variability, this entity could raise differential diagnostic issues with other tumours and malignancies. We describe the case of a 69-year-old male followed at IRCCS Ospedale Policlinico San Martino of Genoa for his previous history of non-Hodgkin lymphoma. A para-aortic mass was discovered during follow-up, which -due to its stability, also after chemotherapy- had been hypothesized to be a non-lymphomatous lesion; given the dimensions and the site, the mass was removed. Histological evaluation showed a nodule limited by a slight fibrous capsule and characterized by a proliferation of medium-sized fusiform cells, with elongated nuclei and scarce eosinophilic cytoplasm. Given the lack of malignant signs and the strong expression of protein S-100, a diagnosis of mesenchymal neoplasia with expression of neural markers compatible with reticular schwannoma was made. The neoplasm has not recurred since its removal. The case we present is, at our best knowledge, the first described in the retroperitoneum, a site where the exclusion of other mesenchymal malignancies is mandatory. The rarity and variability of presentations could create problems of differential diagnosis both with mucinous-producing carcinomas or with other soft tissue tumours, with myxoid or reticular structure. The description of this case could help raise information on this rare neoplasm and help distinguish it from other malignancies, especially in unusual sites.