[Primary hyperparathyroidism with osteitis fibrosa cystica mimicking a malignant bone tumor].

The most common clinical presentation of primary hyperparathyroidism (PHP) is asymptomatic hypercalcemia, and diagnosis of PHP based on the presence of bone manifestations such as osteitis fibrosa cystica (OFC) is increasingly uncommon. OFC occurs in less than 5% of patients with PHP and suggests a more severe or long-standing disease. OFC is characterized by the occurrence of bone pain associated with the finding of specific radiographic changes such as increased subperiosteal bone resorption in the distal third of the radius and middle phalanges, distal clavicular thinning, ‘‘salt and pepper’’ skull, bone cysts, and brown tumors in long bones. Brown tumors result from bone demineralization with osteoclast activation, microhemorrhages, and microfractures, and are so named because of their typical color, due to abundant hemosiderin deposits. Histopathologically, a combination of osteoclastic and osteoblastic activity with cyst formation and many hemosiderin-laden macrophages exists.1 Differential diagnosis of brown tumors includes giant cell reparative granuloma and giant cell tumor (GCT) of the bone. The case of a patient with PHP due to a parathyroid adenoma with brown tumors mimicking a metastatic GCT is reported. A 47-year-old first attended the orthopedic surgery department of a hospital in Castile-La Mancha in May 2008 complaining of pain in the hip and left hand not associated with prior trauma. The patient reported a personal history of dyslipidemia, type 2 diabetes mellitus, arterial hypertension, grade I obesity, and renal colic with calcium oxalate stones. His family history included two daughters who had been diagnosed and undergone surgery for PHP due to adenoma. Plain X-ray of the hip and hand