Endocrine Abstracts

Introduction: Erdheim-Chester disease (ECD) is a rare and aggressive form of non-Langerhans cell histiocytosis (n-LCH). Its etiology is unknown, but recently, BRAFV600E (a proto-oncogene) has been found in more than 50% of cases. This may play a part in chronic uncontrolled inflammation, which is an important aspect of disease pathogenesis.

Case report: A 42-year-old woman complained of generalized weakness, polyuria, and secondary amenorrhea. Biochemistry results revealed elevated plasma osmolality (309 mOsm/l), relatively low urinary osmolality (131 mOsm/l), and no serum AVP. Further results showed that both cortisol (4.3 μg/dl) and ACTH (9.1 pg/ml) were at the lower limit of the normal range. The patient’s free T4 level was low (0.60 ng/dl), while her TSH level was within the normal limits. The prolactin level was increased (92.33 ng/ml), and estradiol was not detected. LH and FSH were low (<0.10 and 0.71 mIU/ml, respectively). The IGF-1 level was also low (62 ng/ml). A hormonal provocation test (CRH, TRH, GRH, and LH-RH) revealed hypothalamic panhypopituitarism. We performed cranial magnetic resonance imaging, which showed signal loss in the posterior pituitary region on T1-weighted images. Furthermore, space-occupying lesions were found in the hypothalamus, brainstem, and temporal lobes when Gad-enhancement was used. Positron emission tomography revealed slightly increased uptake activity in both peripheral lung fields. Video-assisted thoracoscopic surgery was performed for diagnostic purposes to obtain a tissue biopsy. Immunohistochemistry of the lung lesion demonstrated the presence of n-LCH markers, positivity for CD68, and negativity for S-100 protein and CD1a. Bone scintigraphy revealed symmetrically increased osteoblastic activity in the lower limbs. We reached a diagnosis of ECD with pan-hypopituitarism and central diabetes insipidus. BRAF mutation was negative in Sanger sequencing. The patient was treated with 12.5 μg of 1-desamino-8-D-arginine vasopressin (DDAVP) per day for diabetes insipidus. We started regular hydrocortisone 10 mg per day, followed by levothyroxine. For the ECD itself, she was first treated with 40 mg of prednisolone per day, and the tumors slightly decreased in size. However, the dose was tapered rapidly because of worsening of diabetes. The treatment was then commenced with interferon α, but the tumors did not decrease in size. We discontinued the treatment because it induced liver damage.

Conclusion: We present a rare case of ECD that presented with hypopituitarism and diabetes insipidus and involved several organs, including the cerebrum, bones, and both lungs.