Endocrine Abstracts

Case History: A 68-year-old gentleman with hypertension and diet-controlled type 2 diabetes presented in September 2015 with weight loss, fatigue, low libido and cold intolerance.

Investigations: Blood results demonstrated secondary hypothyroidism (TSH 0.59 mU/l (reference range 0.35–5.00), free T4 8.3 pmol/l (ref 9.0–21.0)), hypogonadotrophic hypogonadism (testosterone 1.0 nmol/l (ref 10.0–36.0), FSH 1.5, LH 1.1) and a modestly elevated prolactin (795 mU/l (ref <400)). Short Synacthen test revealed baseline cortisol of 87 nmol/l rising to 376 nmol/l after 30 min. Serum angiotensin converting enzyme and ferritin were normal. MRI pituitary with contrast revealed normal appearances of the pituitary gland.

Results and treatment: Initial working diagnosis was panhypopituitarism of unclear aetiology. He was treated with oral hydrocortisone, levoT₄ and Testogel, with good symptomatic improvement. Six weeks later, he re-presented with a swollen left leg. Doppler ultrasound excluded DVT. To exclude underlying malignancy, CT thorax, abdomen and pelvis was performed. This confirmed extensive inflammatory-looking tissue within the abdomen and pelvis, involving the left ureter and iliac vessels resulting in hydroureteronephrosis. Radiological appearances and subsequent biopsy were in keeping with retroperitoneal fibrosis. A diagnosis of IgG G4-related disease (IgG4 RD) was made on the basis of his clinical presentation, radiological appearances and biopsy findings. Serum IgG4 levels in this patient were within normal limits. He was commenced on high-dose oral prednisolone. Repeat imaging has demonstrated a modest reduction in the inflammatory material around the left ureter, distal aorta and iliac vessels. He remains well and continues on prednisolone at a dose of 5 mg once daily.

Conclusions and points for discussion: IgG4 RD is a collection of disorders characterized by tissue infiltration with IgG4-positive plasma cells and CD4+T lymphocytes, accompanied by fibrosis. It may affect one or more organs, and in this case manifests as retroperitoneal fibrosis and hypophysitis. Lymphadenopathy is often present, alongside weight loss in those with multiorgan disease.

Retroperitoneal fibrosis is common has been associated with hypopituitarism in a number of case reports of IgG4 RD. The relationship is poorly understood, but the underlying pituitary disease is thought to be related to hypophysitis. Diagnosis is based on characteristic histopathological features on biopsy. Serum levels of IgG4 are only elevated in 60–70% of patients. Most patients respond well to glucocorticoid treatment.