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Abstract

GH-producing adenomas clinically are endocrine-active tumors accompanied with acromegaly in most instances. However, GH-producing adenomas apparently unassociated with acromegaly, or so-called silent somatotroph adenomas (SSA), have recently been reported but rarely. The reported cases are characterized by normal or slightly elevated serum levels of GH but without acromegaly. Tumor cells contain moderate, trace or no GH immunoreactivity. We experienced 7 cases of SSA which were not always similar in morphology and pathogenetic mechanism. They could be further divided into the following 3 subtypes. Subtype 1 (N = 2): a moderate number of cells were immunopositive for GH, and GH mRNA was also expressed in moderate or numerous cells. Densely granulated cells were noted. It is assumed that inhibition of hormone release into circulation. Subtype 2 (N = 3): a small number of cells were immunopositive for GH, while GH mRNA was expressed in numerous tumor cells. They were sparsely granulated cells containing fibrous bodies. These findings suggest that posttranslational processing of the gene product may be defective. Subtype 3 (N = 2): Only a scattered number of cells were immunopositive for GH and GH mRNA was co-localized in immunopositive cells. They were sparsely granulated cells containing poorly developed organelles that did not resemble those of typical sparsely granulated GH cells. The findings indicate that adenoma cells are largely immature with minimal GH lineage differentiation.

Clinical and Pathological Aspects of Silent Pituitary Adenomas

“…Similar results were shown in a previous retrospective study, in which silent somatotroph adenomas accounted for 7 of 620 (1%) surgically removed pituitary tumors over 14 years (69). Despite the small sample number, the investigators concluded that, compared with secreting somatotroph adenomas, silent somatotroph adenomas were more frequent in females, presented at a younger age, and were larger, more invasive, and recurred earlier and more frequently.…”

Silent somatotroph tumour revisited from a study of 80 patients with and without acromegaly and a review of the literature

“…In our review of the literature, taking into account the so-called GH silent and the silent type 3 tumours, we found 108 patients (2,4,5,6,7,8,10,11,16,17,18,19,20,21,22,23). Almost all were case-reports and only three series including more than 10 patients have been reported (6,10,11).…”

Silent Corticotroph and Somatotroph Double Pituitary Adenoma: A Case Report and Review of Literature

“…9 Studies have found that in contrast to functional somatotroph adenomas, SSAs tend to occur at a younger age and to be more invasive and recur more frequently. 35 Furthermore, previous case reports have documented the potential for SSAs to become clinically active and to develop signs of acromegaly after initial presentation. 36 The transformation of adenomas from silent to functional forms has also been reported among SCAs.…”