A 35-year-old male, with a previous history of severe plaque-psoriasis who had started treatment with ustekinumab 4 months before, complained of progressive and persistent headache, which was refractory to non-steroidal anti-inflammatory drugs. Brain magnetic resonance imaging (MRI) was unremarkable. One year later, a new MRI was performed due to headache persistence, which revealed a homogenous and diffuse pituitary enlargement of up to 1.1 cm, which extended to the suprasellar region and contacted the optic quiasm, blurring of the pituitary stalk, absence of clear differentiation between the anterior and posterior lobes, and no signs of hemorrhage or adenomas (Figure 1). Visual fields were normal. The patient acknowledged absence of signs or symptoms suggestive of pituitary dysfunction, except for mild libido decrease and erection difficulties. Physical examination revealed multiple psoriatic plaques, with no other remarkable features. Laboratory work-up was consistent with hypogonadotropic hypogonadism, central hypothyroidism, central hypoadrenalism, and GH deficiency, but normality in the rest of the biochemical parameters evaluated (ions, proteins, lipid, renal, and hepatic profiles). Cerebrospinal fluid and work-up of infiltrative and infectious diseases, including sarcoidosis and tuberculosis, were negative. Follow-up MRI performed 6 months later revealed an increase in the pituitary enlargement to up to 1.7 cm. Because etiology of the mass was still unclear, the patient underwent transsphenoidal surgery of the sellar mass, with the purposes of both debulking and obtaining samples for biopsy.
Pathological findings revealed and intense fibrosis and a chronic inflammatory infiltrate of the pituitary gland with a high proportion of lymphocytes and some plasmatic cells, but no evidence of adenoma, granuloma, or acid fast bacilli. Immunohistochemistry pointed to a combined T-cell (CD3+, CD4+, CD8+) and B-cell (CD19+, CD20+) phenotype. Additional immune analysis showed positivity for FOXP3, PD1, and IL-17, and negativity for IgG4 and S-100 protein (Figure 2).
Ustekinumab was withdrawn, with subsequent improvement of headaches. Laboratory work-up after surgery revealed persistent panhypopituitarism, so hormonal replacement therapy was maintained. No other autoimmune disorders were evidenced in the clinical or analytical follow-up evaluation.