We present the case of a 70-year-old woman with a history of diabetes mellitus type 2, dyslipidemia, depression and ibuprofen allergy. She had no toxic habits or workplace exposure to toxins. She was a former housekeeper with no significant family history. Cholecystectomy was performed 30 years previously. She was under regular treatment with metformin, atorvastatin and escitalopram. She presented in the emergency department due to a clinical picture with onset 2 months previously of dry cough, weight loss (10kg), asthenia and anorexia, pain in the right lumbar region and intermittent hematuria in the previous month. Physical examination was normal. Biochemistry results revealed elevated alkaline phosphatase (225IU/l) and gamma-glutamyl transferase (GGT) 119IU/l. Blood count showed hemoglobin at 8g/dl. Chest X-ray revealed a mass in the left upper lobe and multiple bilateral nodules. Computed tomography of chest, abdomen and pelvis showed nodular opacity in the left upper lobe of around 45×35mm, multiple bilateral subpleural nodules, chest lymphadenopathies in various sites and small pleural effusion in both lung bases. The abdominopelvic region showed a large left renal mass, lytic lesion in the right half of the vertebral body and a 15mm nodule in the left adrenal gland. Fiberoptic bronchoscopy was performed, revealing signs of submucosal malignant infiltration in the left upper lobe bronchus. Bronchial biopsy and cytological aspiration were negative for malignancy. Subsequent fine-needle aspiration and biopsy of the left upper lobe gave a pathological diagnosis of lung metastasis of epitheloid clear cell sarcoma of the kidney.

Clear cell sarcoma of the kidney is an uncommon malignancy of unknown histogenesis. It usually occurs in children between 1 and 3 years of age. It is very rare in children younger than 6 months and no cases have been described in adults.1 There are basically 3 kinds of clinical manifestations of clear cell sarcoma of the kidney: urological, general and those caused by paraneoplastic syndromes.2 Important general manifestations include asthenia, anorexia, weight loss (all seen in our patient), low-grade fever, and gastrointestinal symptoms such as nausea, vomiting, constipation and abdominal pain. These symptoms are non-specific and common to other renal cancers.3 The most predominant paraneoplastic symptoms include anemia and Stauffer syndrome, both of which were seen in our patient. Stauffer syndrome is defined as non-metastatic changes in liver function tests, particularly those related with cholestasis (GGT and alkaline phosphatase). Renal cell sarcoma is directly disseminated via the lymphatic system and distant dissemination is either lymphatic or hematogenous.4 Invasion sites, by order of frequency, are lung, lymph nodes, bone, liver, contralateral kidney, adrenal glands and brain. Lung metastases generally appear as multiple nodules, although solitary nodules have also been reported. Bone metastases are lytic or, rarely, blastic. Sites by order of frequency are ribs, vertebrae, iliac crest, femur, humerus and skull5 (Fig. 1).

Fig. 1.

Posteroanterior chest X-ray showing left upper lobe mass and multiple bilateral nodules suggestive of metastasis.

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