Differential Diagnosis
- Single Most Likely Diagnosis
- Prolactinoma (Microadenoma): The patient's prolactin levels are mildly elevated, and the MRI shows a small 2 mm nodule within the left aspect of the pituitary gland, which may represent a microadenoma. The symptoms of stable headaches and regular periods are consistent with a microadenoma.
- Other Likely Diagnoses
- Non-Functioning Pituitary Adenoma: Although the prolactin levels are mildly elevated, the presence of a small nodule on MRI could also represent a non-functioning pituitary adenoma.
- Pituitary Hyperplasia: The mild elevation in prolactin levels could be due to pituitary hyperplasia, although the MRI findings would be less typical for this condition.
- Idiopathic Hyperprolactinemia: The patient's prolactin levels are only mildly elevated, and there is no clear explanation for the elevation, making idiopathic hyperprolactinemia a possible diagnosis.
- Do Not Miss Diagnoses
- Pituitary Apoplexy: Although the patient denies vision changes and has stable headaches, pituitary apoplexy is a medical emergency that can present with sudden onset of severe headache, vision changes, and altered mental status. It is essential to consider this diagnosis, even if it seems unlikely.
- Craniopharyngioma: This rare tumor can present with headaches, vision changes, and endocrine abnormalities, including hyperprolactinemia. Although it is less likely, it is crucial to consider this diagnosis due to its potential for significant morbidity.
- Rare Diagnoses
- Lymphocytic Hypophysitis: This rare inflammatory condition can present with hyperprolactinemia, headaches, and pituitary enlargement. Although it is unlikely, it should be considered in the differential diagnosis.
- Pituitary Metastasis: Metastasis to the pituitary gland is rare, but it can present with hyperprolactinemia, headaches, and other endocrine abnormalities. This diagnosis should be considered, especially if the patient has a history of cancer.