Solitary second metatarsal metastasis as the first site of distant spread in TCC urinary bladder: A case report.

Metastasis to the skeleton is uncommon in muscle-invasive carcinoma of the urinary bladder. When present, it most commonly involves the axial and proximal appendicular skeleton, and acrometastasis (metastasis to hand and foot) is very rare. We report a patient who developed a solitary metastatic lesion of the left metatarsal 2 weeks after radical cystectomy. The lack of suspicion and magnetic resonance imaging findings suggestive of inflammation led to a diagnosis of tubercular osteomyelitis and antitubercular therapy was started. The patient developed nodal metastasis and, because the foot lesion did not respond to treatment, fine needle aspiration cytology from it revealed poorly differentiated metastatic cancer.

INTRODUCTION

Bone metastasis from any malignant tumor usually occurs in the axial and proximal appendicular skeleton, and spread to distal bones (distal to knees and elbows) is unusual. Acrometastasis to the hands and feet is rare, with a 1.7% incidence of foot metastasis in all types of metastatic cancers.[1] Metastasis to hands usually originates from malignancies above the diaphragm (lungs, head and neck) and to the foot arise from subdiaphragmatic primaries (gastrointestinal, genitourinary and uterine).[2] Pedal metastasis most commonly originates from the colon and kidneys and usually involves the tarsal bones (50–73%), with calcaneum being the most common site.[23] These metastatic lesions usually produce non-specific symptoms and are osteolytic in nature. Their rarity, combined with a lack of suspicion, may lead to a delay in diagnosis. We report a patient of muscle-invasive bladder cancer who developed tarsal metastasis as the first site of spread and in whom the diagnosis could not be made until additional metastasis appeared.

CASE REPORT

A 54-year-old non-smoking male underwent radical cystectomy with extended pelvic lymphnode dissection and ileal conduit urinary diversion for muscle-invasive high-grade urothelial carcinoma. The tumor had lymphovascular emboli with microscopic extension into the perivesical fat. All lymph nodes, prostate, seminal vesicle and distal uretric margins were free from tumor (pT3aN0M0). About 2 weeks after surgery, he complained of mild pain, associated with weight bearing, in the left mid foot. This gradually increased in duration and severity and was associated with swelling, redness and tenderness of the left foot. Magnetic resonance imaging revealed altered marrow signal intensity of 2nd metatarsal and T2/STIR sequence suggested osteomyelitis [Figure 1]. His serum uric acid levels were 8.6 mg% and alkaline phosphatase was 193 IU/L. A contrast-enhanced computed tomography scan of the abdomen and pelvis revealed mild left hydrouretronephrosis till aortic bifurcation. In view of localized disease, raised serum uric acid levels and the typical location of pain, anti-gout treatment was started. His symptoms persisted with increased pain, swelling and restriction of mobility. The size of the osteolytic lesion also increased on X-ray [Figure 2a]. A clinical review suggested the possibility of tuberculosis due to its high prevalence, radiological features and immuno-suppressed status in view of malignancy. He was started on antitubercular therapy empirically. Three months later, he developed enlarged left inguinal, retroperitoneal, pelvic and supraclavicular lymphnodes along with a mass in the left pelvic wall, causing sigmoid colon obstruction that necessitated a diverting transverse colostomy. The foot lesion also progressed with extensive lytic lesions of the 1st, 2nd and 3rd metatarsals [Figure 2b]. No other skeletal sites showed increase uptake on the Fluoro Deoxy d-Glucose –Positron Emission T omography scan. Fine needle aspiration cytology of the 2nd metatarsal and left supraclavicular lymph node revealed high-grade metastatic carcinoma and he was started on chemotherapy (gemcitabine and carboplatin) with palliative radiotherapy to the left foot. After palliative radiotherapy and the 1st cycle of chemotherapy, the swelling and pain in the foot and inguinal nodes reduced.

Figure 1

A magnetic resonance imaging scan of the left foot. (a) Axial T1-weighted image of the left mid-foot showing low signal intensity in the 2nd metatarsal base. (b) Axial T2/STIR image showing increased signal intensity inthe 2nd metatarsal and adjoining muscles

Figure 2

(a) Antero-posterior X-ray of the left foot showing a lytic lesion involvingthe base of the 2nd metatarsal. (b) Saggital image of non-contrast computedtomography scan of the left foot showing a necrotic area in the base of the 2nd metatarsal

DISCUSSION

Invasion of lamina propria by transitional cell cancer gives it access to the lymphovascular system, and the pelvic lymph nodes are usually the first sites of spread. Bones, the spine in particular, are the most common site of metastasis outside the pelvis, with multiple lesions being the norm.[4] Our patient developed a symptomatic left foot lesion 2 weeks after surgery as possibly the first sign of metastatic disease. The absence of metastatic disease on imaging, negative nodes on histology, low incidence of foot metastasis and radiological diagnosis of infection contributed to a lack of suspicion of metastasis in this case.

Acrometastasis usually presents with insidious-onset pain, especially on weight bearing, and swelling. A strong clinical suspicion in patients with previous or current advanced malignancies with early histologic diagnosis is required to make a definite diagnosis. Confusion with osteomyelitis, gout, rheumatoid arthritis and ligament strains are well documented.[5] A solitary destructive lesion of bone at sites distal to the knee, as in our case, suggests inflammatory cause because metastasis to these sites is rare. Tuberculosis is a common cause of such destructive lesions of the metatarsal in this part of the world and presents as altered signal intensity of marrow with inflammatory edema of the surrounding muscles. Although abscess formation would have been confirmatory, in the phlegmonous stage, only soft tissue edema is seen. The only feature suggesting a metastasis was previous history of transitional cell cancer of the bladder.

Acrometastasis usually responds well to palliative radiotherapy and chemotherapy. Our patient received carboplatin and gemcitabine-based chemotherapy and 20 Gy of radiation to the left foot. After the palliative radiotherapy and the 1st cycle of chemotherapy, there was a significant decrease in pain and swelling in the foot and inguinal lymph node disease.

CONCLUSION

This report is a testament to the adage that multiple pathologies are less common than multiple manifestations of a single pathology. Acrometastasis, although rare, can be the first sign of metastatic disease. Strong clinical suspicion and early histologic diagnosis may facilitate early diagnosis.