Category: Calcium/Bone Disorders

Monitor: 13

13 - OSTEITIS FIBROSA CYSTICA: A RARE COMPLICATION OF HYPERPARATHYROIDISM MASQUERADING AS METASTATIC BREAST CANCER

Friday, Apr 26
12:30 PM – 1:00 PM

Objective :

Primary Hyperparathyroidism (HPT) classically presents with bone pain, nephrolithiasis, anorexia, and mood disturbances but is largely asymptomatic at diagnosis, in part due to earlier detection of calcium abnormalities on routine blood tests. We however present a case of Osteitis Fibrosa Cystica (OFC), an exceedingly rare skeletal sequela of HPT, presenting as widespread lytic lesions in a patient with breast cancer.


Methods : N/A


Results :

A 54-year-old female with newly diagnosed Invasive lobular breast cancer presented with 1 month of anorexia, failure to thrive, and left thigh pain. On admission, calcium was 15.8mg/dL (8.3-10.2mg/dL), PTH 2926pg/mL (15-65pg/mL), Albumin 3.7g/dL (3.5-5g/dL), Phosphorous 1.7mg/dL (2.4-4.5 mg/dL), Alkaline Phosphatase 451U/L (35-104U/L), 25OH Vit D 19ng/mL (30-150ng/mL), and normal creatinine. Imaging revealed widespread osteolytic lesions in the axial and appendicular skeleton, largest involving the left femur. This was interpreted as extensive lytic metastases from advanced stage breast cancer, and palliation was considered. Endocrine treated HPT with IV fluids and IV bisphosphonate. Sestamibi/SPECT-CT revealed a 1.3cm parathyroid adenoma in the lower right thyroid pole. Surgical resection led to normalization of calcium and PTH with pathology consistent with parathyroid adenoma. Bone biopsy of the femoral lytic lesion was grossly brown in color and showed giant cells rich in osteoclasts with no evidence of malignancy, suggestive of OFC. Cancer stage was downgraded in light of these findings. She underwent curative breast surgery and continues to improve.


Discussion :

OFC is a rare skeletal anomaly (prevalence of 0.1% in the US) that results from excessive stimulation of osteoclasts by PTH, causing subperiosteal bone resorption and cyst formation within poorly woven bone. Hemosiderin deposition within these cysts give a brown discoloration. On imaging, OFC presents with lytic or cystic lesions and histologically as multinucleated giant cells, osteoclasts and fibrosis.  Due to its nonspecific radiographic and histologic appearance, it remains a diagnostic challenge, often mistaken for metastatic cancer or a primary bone neoplasm. OFC reverses with resection of the overactive parathyroid gland. Unfortunately, OFC is not regularly considered in the evaluation of osteolytic bone disease owing to its rarity. Recognizing OFC is critical to avoid unwarranted diagnostic and therapeutic procedures and to appropriately prognosticate confounding diseases.


Conclusion :

Osteolytic bone disease can occur due to a host of pathologic processes. Providers must consider OFC as a potential cause in the setting of HPT to appropriately manage patients in this puzzling scenario.

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Mohammed Qureshi

Endocrinology Fellow
Houston Methodist Hospital
Sugar Land, Texas

Dr. Qureshi is a physician in Houston, TX. He graduated Summa Cum Laude from the University of Houston and went on to attain his doctorate of medicine (M.D.) degree from Texas Tech University Health Science Center School of Medicine.

He completed his residency training in Internal Medicine at Texas Tech University. During residency, he received numerous awards including resident of the year and resident teaching awards. He was called upon to serve as Chief Resident during his final year of residency. Dr. Qureshi has presented at multiple national conferences including the American College of Physicians and the Society of General Internal Medicine.

Dr. Qureshi is currently training at The Houston Methodist Hospital in Clinical Endocrinology. He has been invited to speak and present his abstract at the Endocrine Society’s Metabolic bone disease Conference as well at the American Thyroid Association in Washington DC.

He is anticipated to finish his fellowship training in 2019.