Osseous sarcoidosis masquerading as metastatic disease

Abstract

A 64-year-old woman presented with suspected malignancy, characterized by unexplained weight loss of 2 stone over the preceding year, lethargy and widespread musculoskeletal and back pain for which she was taking Zomorph 10 mg twice daily. She was iron deficient; endoscopy and colonoscopy were unremarkable. A bone scan showed widespread increase in uptake of radioisotope (Figure 1). A computed tomography scan showed multiple lytic lesions throughout the thoracolumbar spine, ribs and iliac blades, consistent with metastatic disease (Figure 2). There was no evidence of cord compression. There were multiple soft tissue nodules throughout both lungs, in tandem with small volume mediastinal lymph node enlargement. Fine needle sampling of a small volume (7 mm) supraclavicular lymph node revealed no malignant cells but surprisingly the sample demonstrated well-formed non-caseating granulomata, staining negative for acid-fast bacilli. Serum angiotensin-converting enzyme levels were high (114 U/litre; normal range 16–53 U/litre), with a calcium level of 2.61 mmol/litre and normal creatinine levels. There was concern that the patient might have dual pathology and so a vertebral body was additionally biopsied, the result again showing a non-caseating granuloma compatible with sarcoid (Figure 3). The diagnosis was revised to systemic sarcoidosis with extensive bony involvement. Prednisolone and bisphosphonate were commenced. There was immediate symptomatic improvement, mirrored by declining serum angiotensin-converting enzyme levels. Interestingly, on commencing treatment there was an initial rapid rise in her alkaline phosphatase level (Figure 4), possibly related to increased bone turnover. At her 2-month review she was virtually free of symptoms. Repeat computed tomography of the chest showed marked regression of the pulmonary nodules but persistence of the skeletal lesions.