POSITIVE SOMATOSTATIN RECEPTOR SCINTIGRAP HY IN A CASE OF GONADOTROPIN-SECRETING ADENOMA - LACK OF RELATIONSHIP WITH THERAPEUTIC EFFECT

Somatotropin and thyrotropin-secreting adenomas are well known for pos itive uptake of radio-labeled octreotide in vivo. this fact is not SO well assessed for gonadotropin-secreting adenomas (GSA). We report one case of positive somatostatin receptor scintigraphy in a woman suffer ing from histologically proven GSA. This 63 year old patient has been suffering for two years of akinetic syndrome when the outcome of diplo pia led to the discovery of a large hypophyseal tumor spreading till V 3 floor and in left cavernous sinus by resonance magnetic imaging (RMI ). Clinical examination showed anterior hypopituitarism and bitemporal hemianopsia. Biologically, blood gonadotropins were decreased more on LH (0,6 UI/l, N > 15) than on FSH (10 UI/1; N > 20). A lack of respon se of gonado-tropins to LHRH with low blood estradiol concentration (< 10 pg/ml) was noticed. Basal blood measurement of alpha subunit was a t 0.17 mu g/l (N = 0.10-1.6) and increased at 0.39 mu g/l after stimul ation by LNRH. Although in low range of normal values, other,hypophyse al hormones were normal except prolactinemia (45 mg/L; N < 20), howeve r stimulated by TRH and related to dopaminergic deconnection; Indium I II labeled octreotide scintigraphy showed an over uptake of the tumor. Three month treatment by octreotide (100 mu g x 3/day subcutaneously) did not allow to decrease significantly FSH concentration or to reduc e the tumoral mass. Incomplete removal of the tumor was performed by t ransphenoidal route. Immunohistochemical analysis revealed positive im munostaining for alpha subunit and FSH beta on numerous cells while th e labeling was slightly less strong for LH beta. These data evoked a G SA. This case record depicts the possibility of detection of GSA by so matostatin receptor imaging. However a positive result does not preclu de of somatostatin analog therapeutic efficiency.