Cushing's disease after surgical resection and radiation therapy for nonfunctioning pituitary adenoma

Phenotype Transformation of PitNETs

Phenotype transformation in pituitary neuroendocrine tumors is a little-known and unpredictable clinical phenomenon. Previous studies have not clearly defined and systematically concluded on the causes of this rare phenomenon. Additionally, the mechanisms of phenotype transformation are not well known. We reviewed cases reported in the literature with the aim of defining phenotype transformation in pituitary neuroendocrine tumors. We present an overview of the wide spectrum of phenotype transformation and its clinical features. We also discuss findings on the potential mechanism of this rare transformation, which may be related to PC1/3, the bioactivity of secretory hormones, gene mutations and the plasticity of pituitary neuroendocrine tumors. Clinicians should be aware of this rare phenomenon and more studies on the underlying mechanisms are required.

Pituitary Adenomas with Changing Phenotype: A Systematic Review

PURPOSE AND METHODS

Phenotype transformation in pituitary adenomas (PA) is a little known and unexpected clinical phenomenon. We describe two illustrative cases and performed a systematic review of cases reported in literature.

RESULTS

Case 1: A 24-year-old woman underwent surgery because of Cushing's disease. A complete tumor resection and hypercortisolism resolution was achieved. Two years later, tumor recurred but clinical and hormonal hypercortisolism were absent. Case 2: A 77-year-old woman underwent surgery due to acromegaly. A complete tumor resection and GH excess remission was achieved. Four years later, tumor recurred but clinical and hormonal acromegaly was ruled out. Search of literature: From 20 patients (including our cases), 75% were female with median age 45 (19) years. Ten patients (50%) had initially functioning PA: 8 switched to NFPA (5 ACTH-secreting PA, 2 prolactinomas and 1 acromegaly) and 2 exchanged to acromegaly from TSH-secreting PA and microprolactinoma. One patient developed a pituitary carcinoma from ACTH-secreting PA. Ten patients (50%) initially had NFPA; 9 developed Cushing's disease (4 silent corticotroph adenomas, 4 null cell PA and 1 managed conservatively). One patient with silent somatotroph PA changed to acromegaly. Treatments before transformation were surgery (80%), radiotherapy (40%), pharmacological (40%) and in 2 patients switching happened without any treatment. Median follow-up until transformation was 72 months (range 12-276).

CONCLUSION

PA can change from functioning to (NF) non-functioning (vice versa) and even exchange their hormonal expression. Clinicians should be aware and a careful lifelong follow-up is mandatory to detect it.

Highly Aggressive and Radiation-Resistant, "Atypical" and Silent Pituitary Corticotrophic Carcinoma: A Case Report and Review of the Literature

Background

Pituitary tumors typically remain silent unless interaction with nearby structures occurs. Rare subsets of pituitary tumors display aggressive phenotypes: highly mitotic, locally invasive, metastatic, chemotherapy and radiation resistant, etc. Disease progression and response to therapy is ill-defined in these subtypes, and their true prognostic potential is debated. Thus, identifying tumor characteristics with prognostic value and efficacious treatment options remains a challenge in aggressive pituitary tumors.

Case Presentation

A 45-year-old female presented with a nonfunctioning corticotropic pituitary macroadenoma with biomarkers suggestive of an “atypical” subtype: Ki-67 of 8–12%, increased mitosis, and locally invasive. Despite resections and radiation, growth continued, eventually affecting her vision. Although histologically ACTH positive, the patient remained clinically asymptomatic. Twelve months later, an episode of Cushing's disease-induced psychosis prompted a PET-CT scan, identifying sites of metastasis. Temozolomide was added to her medical regimen, and her metastatic liver lesions and boney metastases were treated with radiofrequency ablation and stereotactic body radiation therapy, respectively. Systemic treatment resulted in a drop in her ACTH levels, with her most recent scans/labs at 12 months following RFA suggesting remission.

Conclusions

This is a unique presentation of a pituitary tumor, displaying characteristics of both clinically silent corticotropic and “atypical” macroadenoma subtypes. Although initially ACTH positive while clinically silent, the patient's disease ultimately recurred metastatically with manifestations of Cushing's disease and psychosis. With the addition of temozolomide to her treatment plan, her primary and metastatic sites have responded favorably to radiation therapy. Thus, the addition of temozolomide may be beneficial in the treatment of aggressive pituitary tumors.

Cushing Disease After Treatment of Nonfunctional Pituitary Adenoma: A Case Report and Literature Review

We describe a very rare case of nonfunctional pituitary adenoma (NFPA) that exhibited corticotrophic activity after resection and radiotherapy. The possible mechanisms of the transformation from NFPA to Cushing disease (CD) are discussed.A 43-year-old man presented with impaired vision, bilateral frontal headaches, and hyposexuality. He had no symptoms suggestive of hypercortisolism, and 8 am plasma cortisol concentration was 67.88 ng/mL. Brain imaging revealed a 15 × 15 × 21-mm sellar mass suggestive of a macroadenoma. The tumor was resected by transsphenoidal surgery and identified by immunohistochemical analysis as a chromophobic adenoma that did not stain for pituitary hormones. The patient was treated with prednisone and levothyroxine replacement therapy. After a third recurrence, the patient presented with clinical features and physical signs of Cushing syndrome. Plasma adrenocorticotropic hormone (ACTH) and cortisol concentrations were elevated, and there was a loss of circadian rhythms. Inferior petrosal sinus sampling after desmopressin showed the central-peripheral ACTH ratio was greater than 3:1. A repeat transsphenoidal resection was undertaken. Immunohistochemistry revealed ACTH positivity. Three months following surgery, imaging showed little residual tumor, but plasma ACTH remained elevated. He was referred for postoperative Gamma Knife radiotherapy.The immunological activity and biological features of the hormones secreted from a pituitary adenoma vary with time. Because long-term outcomes are unpredictable, postoperative follow-up is essential to detect postoperative transformation from NFPA to CD.