Multifaceted Presentation of the GH-Positive PIT-1 Lineage Pituitary Tumors: Literature Review and Representative Cases

Introduction: Growth hormone pituitary adenomas (GHPA) compose 9 to 11% of all PAs and constitute nearly 20% of all functional PAs. GHPAs classically cause acromegaly. Per the 2022 WHO Classification, unique tumors of PIT-1 lineage differ from a histopathologic, functional, and treatment perspective. Most GHPA are pure somatotroph adenomas causing acromegaly. Other tumor types include clinically silent GHPAs, mammosomatotroph (MSPA) and mixed GH and prolactin (GH-PRL PA), which comprise approximately up to 30% of all GHPA. Studies found these tumors are often larger, more invasive, and less amenable to complete resection. MSPA seem to be more responsive to cabergoline than pure GH counterparts.

Objective: The purpose of this study is to illustrate representative cases of silent growth hormone and prolactin co-secreting GHPAs for an opportunity to learn from nuanced presentation and management.

Materials and Methods: We present three cases treated at our institution with the following tumor types: silent GHPA, MSPA, and mixed GH-PRL adenoma respectively.

Results: All patients presented with a symptomatic pituitary adenoma. The presentation included progressive headaches for the silent GHPA, amenorrhea for the MSPA and optic neuropathy for the mixed GH-PRL PA. Elevated IGF-1 and PRL levels were noted in the non-silent cases, in which GH suppression during glucose challenge confirmed the diagnosis of acromegaly. MRIs are shown in [Fig. 1] and histopathology with H&E and GH staining in [Fig. 2]. Direct endoscopic endonasal approach was the primary treatment for all three patients. Headaches resolved in the silent GHPA patient following surgery. Biochemical remission was achieved for the MSPA case. PRL improved but did not normalize postoperatively in the mixed GH-PRL PA; cabergoline then led to PRL biochemical control.

Fig. 1 Pre (A, C, E) and postoperative postcontrast MRI (B, D, F) of representative patients. (A and B) are of silent GHPA, (C and D) are of mammosomatotroph PA, (E and F) are of mixed-cell GH-PRL PA.

Fig. 2 Histopathology including H&E (A, C, E) and GH (B, D, F) stains of representative patients. A and B are of silent GHPA, C and D are of mammosomatotroph PA, E and F are of mixed-cell GH-PRL PA

Conclusion: We present three cases with worrisome PA histopathology that had a favorable postoperative course at our institution. We emphasize the importance of measuring IGF-1 levels in all patients with PA.

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Artikel online veröffentlicht:
07. Februar 2025