[Coincidence of bone infarct and aggressive bone metastasis]

A 42-year-old male patient presented with a history of persistent pain in the right femur without trauma of 2 months, duration and an episode of bloody stools 3 months earlier with no clinical findings upon examination. X-rays and CT scan revealed a circumscribed lesion with sclerosis and periostal reaction in the right proximal femur. A three-phase bone scan showed a massive hot spot in this area. Primarily differential diagnoses included a Brodie's abscess and/or a tumor. An excisional biopsy of the area was performed and revealed the coexistence of a bone infraction and the metastasis of an adenocarcinoma of unknown origin. The lesion in the bone was resected, filled with autogenous cancellous bone and stabilized with a plate. Further intensive screening with CT of the abdomen, gastroscopy and colonoscopy led to the primary tumor, an adenocarcinoma at the rectosigmoidal junction. No other metastases were detected. This patient presented with severe pain an radiologically divergent findings: a presumably benign process on radiography, but a massive hot spot on scintigraphy. Further procedures such as a CT scan and/or MRI had to be undertaken. If the analysis includes the differential diagnosis of a malignant process, a biopsy must be obtained, and if this reveals a metastasis, the primary tumor must be sought.