Pituitary adenomas are tumors of the anterior pituitary gland. Most are slow-growing and benign. They are classified based on size or cell of origin and described as microadenoma, macroadenoma, or giant tumors. Microadenomas are usually less than 10 mm in size, while macroadenomas are larger than 10 mm. Giant pituitary tumors are bigger than 40 mm.
Adenomas are further classified as either functioning or non-functioning. Functioning pituitary adenomas are composed of a cell type that causes them to secrete one or more of the multiple hormones found in the anterior pituitary. There are also non-functioning adenomas that do not secrete hormones but can compress the surrounding areas of the anterior pituitary leading to mass effect or hormonal deficiency.
Presentation of pituitary adenomas depends on the tumor size and functional status. Microadenomas are usually an incidental finding on MRI of the head. Patients are usually asymptomatic unless the tumor is hormonally active. Pituitary macroadenomas present with mass effect and may be hormonally deficient or hormonal excessive.
Patients presenting with mass effect may report symptoms of visual impairment, headache, or hormonal deficiency. Gonadotropin deficiency presents as amenorrhea in females and erectile dysfunction in males. Growth hormone deficiency (GH) in adults usually leads to fatigue and weight gain. Thyroid-stimulating hormone (TSH) deficiency symptoms include weight gain, fatigue, cold intolerance, and constipation. Adrenal corticotropic hormone (ACTH) deficiency presents with fatigue, arthralgia, weight loss, low blood pressure, dizziness, nausea, vomiting, and abdominal pain.
Biochemical evaluation is needed for diagnosis, including measurement of the various hormones such as prolactin, TSH, free T4, follicle-stimulating hormone (FSH), IGF-1, GH, ACTH, estradiol, testosterone, BMP, and fasting early morning cortisol. Providers may also order screening tests for Cushing disease or additional imaging tests to rule out differential diagnoses such as: meningioma, glioblastoma, astrocytoma, ependymoma, lymphoma, Rathke cleft cyst, or other conditions.
Spontaneous regression of pituitary adenomas is known to frequently occur in hormonally active tumors but is rare in cases of nonfunctioning adenoma. The underlying mechanism of tumor regression is not clear. Some studies have suggested that events such as apoplexy, hormonal fluctuations due to childbirth, anticoagulation therapy, stress test of pituitary hormone or bromocriptine treatment could facilitate spontaneous regression of a functional pituitary adenoma. Less data is available on regression in nonfunctioning macroadenomas or incidentalomas, however it is known to occur.
Pituitary adenomas are reportable tumors in the United States. Case finding can be tricky in cases when patients have a previous history of benign tumors or present to your facility with a remote history of disease not found on current imaging. The diagnosis of pituitary adenomas is typically made clinically and from imaging studies and may not be identified on routine or automated case finding processes. The Cancer Registry should review and confirm that the appropriate ICD-10 codes are included in the disease index for pituitary adenomas to ensure completeness and accuracy of case reporting. Other local or state reporting rules may also apply.
According to SEER, pituitary adenomas are reportable even if the tumor regresses without treatment. For example, if a patient was diagnosed in 2010 on imaging and treatment was not given, and subsequently presents to your facility years later with no evidence of tumor on MRI, it is reportable even though it regressed.
The SEER rules for solid tumors, benign CNS tumors, date of diagnosis and class of case will help you to further determine reportability at your facility. Text fields should describe the radiographic, and clinical course of treatment, including observation or treatment with bromocriptine that was recommended, offered, or received.
If you are unsure whether your Registry is capturing all reportable pituitary adenomas you may consider performing an audit using the disease index, filtered on the ICD-10 code and then randomly compared to the Cancer Registry accession register to determine if there are any gaps.
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