FINAL DIAGNOSIS Metastatic urothelial carcinoma to the calcaneus
The 7th most common cancer worldwide, bladder cancer occurs at the highest incidence rate in Western Europe, North America, and Australia, and is more common in men. The most common type is urothelial (transitional cell) carcinoma, which constitutes over 90% of cases in the US. Risk factors include tobacco smoking and exposure to aromatic amines, in additional to several medications and chronic infection by Schistosoma haematobium (1).
Although most patients present with microscopic hematuria, gross hematuria occurs in up to 85% of patients. Other symptoms may include dysuria, urgency, and frequency. Diagnosis is confirmed by cystoscopy with biopsy or resection of the lesion including sampling of the muscular bladder wall (1). Pelvic lymph node metastases have been identified in up to 25% of invasive tumors (2).
One autopsy-based study identified metastatic lesions in 68% of 367 patients with muscle-invasive bladder cancer. Most frequent metastatic sites included regional lymph nodes, liver, lungs, bone (32%), peritoneum, pleura, kidney, adrenal gland, and bowel (3). Another retrospective series examining specifically boney metastases in muscle-invasive bladder cancer found 14.5% of patients to have bone metastases at presentation, with the pelvis and spine representing the most common sites (4).
Although bone metastases from urothelial carcinoma are not entirely uncommon, distal metastases are unusal. A PubMed search returned only two published cases: one of metastasis to a metatarsal and another of metastasis to the calcaneus (5,6). Furthermore, metastatic disease of the foot, of any primary, is exceedingly rare. Several older studies reported rates of metastases to the foot of 0.003 to 0.01% (8, 9, 10). A recent review of 153 foot and ankle tumors over 20 years at Stanford University noted only two cases, both of renal cell carcinoma origin, for an incidence of only 1.3% (7). In another recent review, the incidence of foot and ankle metastasis was 2%. In Maheshwari et al's series, the most common primary site was the genitourinary system and one index case described a patient similar to ours with metastatic urothelial carcinoma. The authors also reviewed the literature and found 278 mentions of metastatic lesions of the foot. Although metastases from 31 different primary malignancies were described, the genitourinary system again accounted for a significant proportion of cases (14.4% kidney and 8.7% urinary bladder). The hind foot, particularly the calcaneus and talus, was most commonly involved. Distal metastases were associated with extensive metastatic disease and poor survival (10).
Contributed by Hannah Kastenbaum, MD