Endocrine Abstracts

Background

Currently, serious complications of secondary hyperparathyroidism (sHPT) are rare due to early diagnosis and more effective treatments. These complications include osteitis fibrosa cystica, which is characterized by bone resorption and brown tumors. Depending on the location, they can cause pain or compressive symptoms.

Case report

We report a case of a 41-year-old black woman with a past medical history of arterial hypertension diagnosed at 25 years-old and chronic kidney disease (CKD) diagnosed at 35 years old, undergoing hemodialysis treatment. sHPT was present since the diagnosis of CKD, with PTH values consistently > 1000 pg/ml despite the use of cinacalcet and paricalcitol thrice-weekly during hemodialysis. In March 2020, during a visit to relatives in Angola, the patient had an intense and sudden dorsal pain. She developed progressive paraparesis and hypoesthesia of the lower limbs and fecal and urinary incontinence. Due to limited health care assistance and a travel ban due to the COVID-19 pandemic, medical evaluation was only possible six months later in Portugal. At hospital admission in September 2020, she presented with paraplegia and hypoesthesia of the lower limbs and fecal and urinary incontinence. CT-scan revealed bone lesions in three ribs, ischiopubic ramus, left acetabulum, and D7 and D11 vertebral bodies, with spinal canal invasion. A pathologic fracture in D11 and multiple millimetric lesions in some vertebral bodies and iliac bones were also detected. The lesions presented with a dominant blastic component. Serum levels of PTH were 1310 pg/ml (18.5–88.0 pg/ml) with normal total corrected calcium, vitamin D and phosphate levels. Bone biopsy was performed in one of the affected ribs, reporting histological abnormalities consistent with brown tumors. The 99m Tc-sestamibi scintigraphy detected increased metabolic activity in the inferior left lobe of the thyroid gland and in the bone lesion of the first costal arch. A subtotal parathyroidectomy was performed. On the first day post-surgery, PTH levels normalized (56.73 pg/ml). The histopathology report confirmed hyperplasia of the parathyroid glands. Currently, the patient is under motor rehabilitation and medicated with calcium, cholecalciferol, and alfacalcidol.

Conclusion

Despite being rare and benign, brown tumors can cause severe morbidity and should be considered in the differential diagnosis of bone lesions. Persistent sHPT unresponsive to medical therapy with calcimimetics and vitamin D derivates is a significant risk factor and should prompt a timely referral to parathyroidectomy. Unfortunately, the COVID-19 pandemic caused delays in consultations and surgeries reducing the possibility of early interventions.