This article is more than 5 years old. Information may no longer be current.

A 53-year-old woman with foot pain

Issue: November 2013

ByAndrew R. Hsu, MD

BySteven Gitelis, MD

BySimon Lee, MD

ByChristopher E. Gross, MD

Add topic to email alerts

Receive an email when new articles are posted on

Please provide your email address to receive an email when new articles are posted on .

Subscribe

Added to email alerts

You've successfully added to your alerts. You will receive an email when new content is published.

Click Here to Manage Email Alerts

You've successfully added to your alerts. You will receive an email when new content is published.

Click Here to Manage Email Alerts

Back to Healio

We were unable to process your request. Please try again later. If you continue to have this issue please contact customerservice@slackinc.com.

Back to Healio

 

Sanjeev Bhatia

 

Andrew R. Hsu

A 53-year-old woman presented to the office complaining of a 1-year history of right foot pain. She did not recall any inciting trauma or injury. Her pain progressively worsened to the point where she could no longer jog for more than 1 mile before having severe pain. She described the pain as a deep ache worse with ambulation and exercise. Pain was present at night and recalcitrant to oral anti-inflammatory medications. Her past history was remarkable for breast lumpectomy surgery 17 years prior and low-grade melanoma excision with negative margins from her left thigh 15 years ago.

Examination and diagnostic studies

On physical examination, the patient had a slightly antalgic gait, favoring her non-affected left leg. She endorsed moderate tenderness to palpation along the dorsal and central aspects of her foot. She had a moderate fullness near her midfoot dorsally. She was neurovascularly intact throughout her foot and ankle with strong dorsalis pedis and posterior tibial pulses.

Figure 1. Initial (A) anteroposterior, (B) oblique and (C) lateral radiographs of the right foot demonstrate a destructive bone lesion of the third metatarsal.

Images: Gross E, et al.

Figure 2. (A) Coronal, (B) axial and (C) sagittal T1 post-gadolinium MRI cuts demonstrate a 3.1x3.3x6.5 cm expansile mass in and around the third metatarsal with minimal remaining cortex intact in the articular surfaces at the head and base of the third metatarsal.

Radiographs and MRI of the foot were obtained (Figures 1 and 2). Inflammatory labs including serum C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) and serum white blood cell (WBC) were within normal limits. The patient was taken to the operating room initially for a core-needle biopsy of the right foot mass. Her pathology is shown in Figure 3.

Figure 3. (A) Low- and (B) high-power hematoxylin and eosin slides of the initial core-needle biopsy. Cells are highly pigmented and consist of medium to large poorly cohesive, but epithelioid cells with abundant pigmentation.

What is your diagnosis?

See answer on next page.

Metastatic melanoma

The burden of primary and metastatic disease to the foot and ankle is small. Due to the rarity of these pathologies and the number of pathologic entities that can localize to this region, diagnosis and surgical management can be challenging. Approximately 8% of benign and 5% of malignant soft tissue tumors of the body occur in the foot and ankle, according to a series by Kransdorf of 39,179 patients. In a study by Chou and colleagues that reviewed 153 cases of foot and ankle tumors, 60.8% were benign. The most common bone tumor diagnosis was giant cell tumor (GCT), and the most common soft tissue tumor was pigmented villonodular synovitis (PVNS) and GCT of a tendon sheath. Of the malignant tumor types, chondrosarcoma and osteosarcoma were the most prevalent bone tumors and synovial cell sarcoma was the most common soft tissue tumor. This study echoed the results of a larger series by Murari and colleagues of 255 primary bony neoplasms of the foot in which chondrosarcoma (52%) and osteosarcoma (17%) represented the most common malignant foot tumors.

Steven Gitelis

Metastatic disease in the foot and ankle is extremely uncommon in the reported literature. Metastases to the foot occur at one-third to half the rate of metastases to the hands, with a rate of 0.01% of primary malignancies with metastases to the foot and ankle. These acrometastases are usually pre-terminal events and represent a larger metastatic burden of disease. In a series of 14 patients with metastatic disease to the foot and ankle, Maheshwari and colleagues found that the mean survival after a diagnosis of metastastic disease was 14.8 months (range, 1 month to 54 months). The most common metastasis from a primary organ system is the genitourinary system with over half of the cases reported.

Metastatic melanoma to the foot and ankle is rare, as it has only been reported six times in the literature at a rate of 2.6% of all malignant lesions to the foot. In malignant disease, most lesions are found in the calcaneus (31.1%), while lesions in the metatarsals represent 25.3% of diagnoses. Malignant melanoma occurs in patients aged 30 years to 60 years and most commonly in women during their menopausal years. When a malignant melanoma does metastasize, one of the more common distant sites is bone (6.9% of patients with malignant melanoma). Metastases to the axial skeleton represent 80% of bony lesions. Histologically, there is an osteolytic transformation with involvement of the bone marrow.

Christopher Gross

It is difficult to diagnose foot and ankle metastases early in their presentation as there is often a wide variety of vague symptoms and complaints. While most patients with neoplasms in the foot and ankle complain of pain as their primary symptom as did our patient, it is difficult to distinguish the primary sources of pain due to referred pain and adjacent pathology. This is due to the rather numerous and compact compartments in the foot that share many neurovascular structures. In one study by Hattrup and colleagues, the mean delay of diagnosis was 93 months with one patient not having a diagnosis for 172 months from presentation. The authors concluded that this delay may be attributed to a combination of the rarity of the disease, and that early manifestations of metastases may mimic other musculoskeletal pathologies such as degenerative joint disease. Initial symptoms may include swelling, warmth and erythema due to the proximity of all the structures in the foot. However, these symptoms may be credited to osteomyelitis, gout, abscess, tenosynovitis or other more common entities such as trauma or arthritis.

Imaging

When neoplasms of the foot and ankle are suspected, it is important to first order plain radiographs of the affected area. Roughly 80% of patients with foot metastases present with a lytic bone lesion on radiographs with little involvement of the periosteum. The lesion can extend into the soft tissue and there is often cortical ballooning as the neoplasm expands. The joint is rarely involved and is usually not crossed by the tumor. Bone complications of metastatic melanoma include: pathologic fracture (22.5%), cortical destruction (46.6%) and soft tissue involvement (12.5%). In our patient, the third metatarsal dorsally had a thin cortical shell that was expanded by the malignant tissue. The lesion did not penetrate the juxta-articular subchondral bone proximally or distally.

Simon Lee

On MRI, these lesions have an intermediate/high signal intensity on T1-weighted images and mixed high- and low-signal intensity on T2-weighted images. Post-gadolinium imaging shows heterogenous uptake of the contrast.

Operative management

The condensed compartments of the foot make successful resection of neoplasms challenging. Due to the poor prognosis of patients with metastatic disease in the foot and ankle, often palliative treatments, such as radiation therapy, are used in order to preserve function and reduce pain. Surgery is reserved for patients with isolated lesions who have an estimated prolonged survival. In our case, this patient had an isolated metastasis (based on PET scan) and a disease-free interval of 15 years. This disease-free interval has yet to be described in the literature. As this scenario is rare, it may suggest a better prognosis and a reason for aggressive surgical management.

For many orthopedic oncology cases, it is important that a multidisciplinary approach be undertaken in order to offer the best chances for limb salvage and survival for the patient. Our patient was carefully evaluated by medical and surgical oncology. The options of removing her melanoma included a third ray resection amputation vs. a higher-level tarsal amputation recognizing that a ray resection amputation would result in close margins. After a lengthy discussion with the patient, the decision was made to pursue a modified third ray resection with orthopedic oncology and foot and ankle surgery services.

Our initial incisions were centered over the dorsum and plantar aspect of the third metatarsal (Figure 4). All neurovascular structures were preserved. The tumor and the margins were readily visible as the mass was dark brown-black in color. After dividing the fascia, a plane was developed between the tumor and the surrounding metatarsals. The plantar muscles were incised and the third metatarsal joint was disarticulated.

 

Figure 4. Intraoperative photographs (A) after en-bloc resection of the tumor with (B) specimen demonstrate a destructive pigmented tumor. (C) Immediate post-surgical photograph of foot reconstruction after reconstruction and primary closure is shown.

To close the defect as well as correct the subsequent deformity, the lateral cuneiform was excised. We were then able to subsequently mobilize the second and fourth rays in order to close down the defect. A bony synostosis between the cuneiforms and the base of the second and fourth metatarsals was performed by manually compressing the base of the metatarsals. We were then able to suture together the distal second and fourth metatarsophalangeal joints and the remaining deep tissue and skin edges were closed primarily.

Intraoperative pathology (Figure 3) demonstrated a highly pigmented lesion consisting of medium to large poorly cohesive, but epithelioid, cells with abundant pigmentation. The cells had a high nuclear to cytoplasmic ratio and marked pleomorphism. Some cells had nuclear pseudoinclusions and numerous mitoses were readily found.

Follow-up

Postoperatively, the patient was made nonweight-bearing for 6 weeks in a post-mold splint. At 6 weeks, she was transitioned to a CAM boot walker with partial weight-bearing for 2 weeks. At 8 weeks, she was allowed to weight-bear as tolerated in a regular shoe. She initially had minor superficial wound healing issues that resolved with local wound care. She had a PET-CT scan of her chest, abdomen, and pelvis that did not demonstrate a primary source of cancer nor any additional metastases. After discussion with her medical oncologist, the patient was sent to radiation oncology for a round of radiation therapy. She was also placed on a single-drug chemotherapy regimen. On most recent follow-up, the patient is doing well and ambulating with minimal pain in a regular shoe.