Silent GH pituitary tumor: diagnostic and therapeutic challenges

Abstract

Silent GH pituitary tumors are characterized by the absence of clinical features of acromegaly, normal to slightly elevated GH and/or IGF-1 levels, as well as immunohistochemical expression of GH. The diagnostic and the therapeutic challenges of these "silent" GH tumors are illustrated in this case report, supported by a literature review. A 20-year-old woman presented with visual disturbances related to an invasive macroadenoma but without clinical and biological signs of GH hypersecretion. After two surgeries, a residual tumor remained in the right cavernous sinus. According to the recent classifications, the histopathological diagnosis was a sparsely GH-PRL atypical adenoma or invasive and proliferative (Ki-67 index: 4%) and p53 positive (1%) grade 2b tumor, with high expression (>75% of the cells) of somatostatin receptors type 2A and 5. From this case and the review of the literature, an invasive macroadenoma in young women requires: the preoperative determination of plasma GH and IGF-1, the immunohistochemical detection in the tumor of GH, PRL, somatostatin receptor expression and the evaluation of the proliferation (mitoses count, Ki-67 and p53 indexes). The suspicion of an aggressive behavior needs a particular follow-up. In the case of tumor remnant, a postoperative treatment such as radiotherapy and/or somatostatin analogs must be considered.