Thyroid hemiagenesis coexisting with brain cavernoma and pituitary Rathke's cleft cyst

Sir,

Cavernous hemangiomas are benign vascular lesions of the brain and other organs that affect approximately 0.4-0.8% of the population. Though symptoms are usually noted in the third or fourth decade; some cases have been reported in childhood.[1]

A 24-year-old Caucasian female initially presented to our hospital at the age of 16 years with loss of consciousness following extensive physical activity. Brain magnetic resonance imaging (MRI) revealed the presence of a right parietal cavernous hemangioma associated with a tiny bleed [Figure 1]. Electroencephalography (EEG) was normal. A cerebral angiogram ruled out an arteriovenous malformation and aneurysmal dilatation.

Figure 1.

T2 MRI image showing a cavernoma in the right peritrigonal white matter measuring 8.5 × 7.5 mm²

Three years after diagnosis, a follow-up MRI showed no recent bleed in the cavernous hemangioma but revealed an enlarged pituitary gland. Magnetic resonance imaging of the sella was obtained which showed the presence of a Rathke's cleft cyst between the anterior and posterior pituitary, 1.4 × 0.7 × 0.6 cm³ in size and deviating the pituitary stalk superiorly [Figure 2]. We found no evidence in literature that addressed co-existence of a Rathke's cleft cyst with a cavernous hemangioma. A Rathke's cyst is derived from remnants of Rathke's pouch; sellar or suprasellar cystic lesions lined by epithelium. The incidence is 11-33% on postmortem examination. The cyst may compress the pituitary stalk, resulting in hyperprolactinemia.[2] Hormonal work up revealed high prolactin, with normal thyroid-stimulating hormone (TSH), insulin-like growth factor-1 (IGF-1), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and cortisol. The patient denied having any symptoms that could be associated with hyperprolactinemia despite a prolactin level of 156 ng/mL. She was started on a treatment with a dopamine receptor agonist, cabergoline, for a total duration of 6 weeks. The repeat prolactin level was normal at 6 weeks after the treatment. At this point, we carried out a physical examination where a non tender, mobile, node that was less than 1 cm was palpated in the left hemi thyroid. It was less than 1 cm in size, mobile, and nontender. Serum TSH and free thyroxine (T4) were normal. Ultrasound of the thyroid revealed agenesis of the right hemi thyroid and prominent left hemithyroid that contained cysts [Figure 3].

Figure 2.

MR sella showing an enlargement of the pituitary gland, which contains a cyst located between the anterior and posterior pituitary. The cyst shows hyperintense signal on T1 (a) and shows no enhancement post gadolinium (b)

Figure 3.

Thyroid ultrasound: (a) Reconstructed image comparing the left and right thyroid lobes, showing absence of thyroid tissue on the right. The left hemithyroid contains multiple cysts (b) Absence of the right thyroid lobe

Thyroid hemiagenesis is the congenital absence of one of the thyroid lobes, estimated to affect 0.02-0.16% of the population, with around 300 cases reported in literature. This condition tends to occur in females more than in males, the left lobe is more often affected than the right lobe, and it predisposes the affected patient to associated thyroid pathologies such as hyperthyroidism, hypothyroidism, nodular goiter, Hashimoto thyroiditis, Graves's disease, and papillary thyroid carcinoma.[3,4]

We believe that the occurrence of all three pathologies in a single patient may have a genetic basis, but are unclear at the moment as to what it could be.