Introduction

Pituitary tumor apoplexy is a clinical syndrome characterized by an abrupt onset of signs and symptoms that occur with rapid expansion related to hemorrhage or infarction of a preexisting adenoma [4, 5]. Although most pituitary tumors are microadenomas, most cases of pituitary tumor apoplexy are associated with macroadenomas [5, 7]. There has been only one case of pituitary apoplexy in the presence of a microadenoma reported previously [2]. The purpose of this paper is to present and illustrate three cases of pituitary apoplexy that occurred in patients with microadenomas. Review of these cases indicates that it is possible that many apoplectic events occurring in association with microadenomas are missed.

Case reports

Case 1

This 23-year-old woman initially presented to an outside institution with a 2-month history of intractable headaches after the delivery of her first child. During the more severe headaches, she experienced associated nausea. She reported having intermittent dizziness, light-headedness, visual disturbance, and blurry peripheral vision. She had had normal menstrual periods in the past and had no difficulty conceiving. She was not breastfeeding her child, and her menstrual periods had resumed. Her visual acuity and the results of her visual field examinations and the rest of her neurological examination were normal. Her headaches were initially presumed to be migraines, but because of a sudden increase in their severity 2 months after presentation, magnetic resonance (MR) imaging was performed. The MR imaging demonstrated a high signal intensity lesion on T1-weighted image within the substance of the pituitary consistent with hemorrhage (Fig. 1a, b). The characteristics seen on the MR imaging seemed most compatible with a small apoplectic pituitary tumor or Rathke cleft cyst [1]. Conservative management was undertaken, and she was referred to our institution for further evaluation.

Fig. 1
figure 1

Case 1. a, b Magnetic resonance images obtained at initial presentation showing features consistent with hemorrhagic lesion of the sella. a Sagittal T1-weighted image without contrast enhancement. b Coronal T1-weighted image with contrast enhancement. c, d Magnetic resonance images obtained at 8-month follow-up showing resolution of the lesion

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At an 8-month follow-up with the senior author, the MR imaging scan showed remarkable regression of the lesion, which made a diagnosis of apoplexy into a small tumor more likely (Fig. 1c, d). At 2-year follow-up, she was having normal menstrual periods, and her pituitary function was normal.

Case 2

This 32-year-old previously healthy woman presented at our clinic after 1 week of severe headache localized to the right frontal area and some associated nausea. The patient reported that she had had oligomenorrhea since age 13; she had not had galactorrhea. A history of polycystic ovarian syndrome and tension-type headaches was noted. The patient had no history of previous pituitary tumor or family history of pituitary tumor. On examination, she had no visual acuity problems or visual field deficits. The other results of her neurological examination were also normal. A complete pituitary endocrine panel was obtained, and the patient underwent dedicated pituitary MR imaging with and without contrast enhancement (Fig. 2a–c). Necrosis and hemorrhage in the sella were seen. Given the fact that the results of endocrinological studies were normal and her symptoms were improving, she was monitored conservatively with planned 3-month follow-up.

Fig. 2
figure 2

Case 2. Sagittal (a) and coronal (b) T1-weighted magnetic resonance (MR) images without contrast and coronal T1-weighted MR image with contrast enhancement (c) obtained at initial presentation showing necrosis and hemorrhage into the sella. Follow-up images obtained 3 months later (d, sagittal T1-weighted MR image without contrast; e, coronal T1-weighted MR image without contrast; f, coronal T1-weighted MR image with contrast) show resolution of the necrosis and interval decrease in the size of the pituitary

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A second MR imaging scan 3 months later showed an interval decrease in the size of the pituitary gland, with the areas previously described as necrosis and hemorrhage now resolved (Fig. 2d–f). The patient reported her headaches had resolved, and endocrine studies showed normal results.

Case 3

This 27-year-old previously healthy mother of four was referred to our clinic almost 10 months after delivering her last child. She had originally presented at an outside hospital 20 months earlier, prior to her pregnancy, with galactorrhea and oligomenorrhea. Her serum prolactin level was elevated at 86 ng/ml. At that time, MR imaging with and without contrast enhancement showed a normal-sized pituitary gland with microprolactinoma (Fig. 3a, b). The patient was started on bromocriptine (2.5 mg/day orally) and conceived within a few months. The patient discontinued use of bromocriptine after she realized she was pregnant. Nine months postpartum, the patient experienced a severe headache, nausea, vomiting, and occasional tunnel vision. MR imaging performed at an outside facility showed the pituitary gland now with a new area of subacute intrapituitary hemorrhage consistent with pituitary apoplexy (Fig. 3c, d).

Fig. 3
figure 3

Case 3. a, b Sagittal (a) and coronal (b) T1-weighted magnetic resonance (MR) imaging studies with contrast enhancement obtained at initial presentation, before pregnancy, showing small adenoma in the left part of the pituitary gland. c, d Coronal T1-weighted MR imaging studies without (c) and with (d) contrast enhancement showing hemorrhage into the area of the previously diagnosed tumor

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The patient was referred to our institution for transnasal, transsphenoidal resection of the pituitary adenoma. Findings during the operation were consistent with a diagnosis of pituitary apoplexy. Upon opening of the dura mater, there was immediate expression of old hemorrhage. Tissue was sent for pathological analysis, and a diagnosis of prolactin-secreting pituitary adenoma was confirmed. Three days after the operation, the results of her neurological examination were normal, and the patient was discharged home. At a follow-up examination 1 year later, her endocrine levels were all normal.

Discussion

The diagnosis of pituitary apoplexy is clinically suspected and then confirmed by imaging [3, 5, 6]. In all three of these cases, the patient had an abrupt onset of headache. MR imaging studies supported the diagnosis of pituitary apoplexy into a microadenoma, demonstrating resolution of intrasellar hemorrhage on follow-up studies in two patients. The third patient had histological evidence of hemorrhagic tumor removed at surgery. Although tumor was histologically confirmed in only this patient, given the prevalence of pituitary adenoma, this was a more likely diagnosis than Rathke cleft cyst or other entities in the other two patients as well [1]. The two other cases were managed conservatively, given the late referral in case 1 and the improving symptoms and normal endocrine studies at presentation to our clinic in case 2.

Pituitary tumor apoplexy is classically associated with macroadenomas. Most cases (81%) of pituitary apoplexy occur in patients with no history of pituitary tumor [5, 6]. With no prior history of adenoma, it may be difficult to distinguish pituitary apoplexy in a microadenoma from other causes of headache, and the pituitary apoplexy into microadenomas may be misdiagnosed. Review of these cases poses the possibility that pituitary apoplexy in microadenomas may be much more common than appreciated. Clinical suspicion, with appropriate endocrinological and pituitary imaging, is necessary to establish the diagnosis.