Jay Lieberman DPM, FACFAS, Director of Podiatric Medical Education, Northwest Medical Center Alex Andes 1st Year Resident Foot and Ankle Surgery, Northwest Medical Center

Case Study: Bizarre Foot bone tumor A nineteen year old athletic male presented with a chief complaint of a “large lump” along the top of his right foot. Patient stated he began to notice this mass approximately one year ago and it had progressively increased in size over time. He complained of pain and discomfort especially during activities. He also expressed a concern that the mass had become so large that it is difficult for him to fit into his regular shoe gear.

Patient reported a history of recurrent lateral ankle sprains and was uncertain if those injuries were associated with his current complaint.

Past Medical History: Right elbow fracture

Allergies: No known drug or environmental allergies

Medications: None

Social History: Denies intake of tobacco but admits to occasional consumption of alcohol and caffeinated beverages.

Family history: Noncontributory

Lower Extremity Examination: A prominence was identified along the dorso-lateral aspect of the right foot. Upon manipulation, this solid mass was found to be secured to its current location. Tenderness upon palpation was noted along the dorso-lateral right foot. No open lesions, edema or erythema were noted. Epicritic sensations were grossly intact. Dorsalis pedis and posterior tibial pulses were palpated and graded +2/4. Examination of the left lower extremity was unremarkable.

Radiographic Findings: AP, lateral and medial oblique plain film x-rays of the right foot revealed a well-circumscribed mass along the dorso-lateral foot. This mass demonstrated primarily a similar radiopacity to that of his surrounding bony structures with the exception of some central radiodense areas. No fractures or dislocations were identified. A CT scan of the right foot was also obtained which relayed similar information.

Click on the images for a full-screen view
Figure 1. Pre-Op AP Right	Figure 2. Pre-Op MO Right Foot

Treatment options were discussed in detail with the patient and his mother. The importance of excisional biopsy to determine the benign versus malignant nature of this mass was also explained. The patient opted to undergo a surgical procedure of excision of bone tumor/neoplasm from his right foot. All risks, benefits, complications and alternatives were described. The patient consented to the above mentioned procedure and all pre-operative labs and paperwork were completed.

Procedure- Excision of bone tumor/neoplasm, right foot

The right foot and ankle were exsanguinated utilizing a sterile esmarch bandage and the tourniquet was inflated to 250mmHg. An approximate 3.5 cm. Care was taken to avoid all neurovascular structures. Once all tendons, nerves and blood vessels were retracted, the incision was deepened through the muscle belly of the extensor digitorum brevis muscle belly.

At this juncture, a solid white mass was visualized and noted to have an appearance similar to that of bone and cartilage. This mass was freed from its soft tissue attachments utilizing a #15 blade scalpel as well as a collar and crown instrument. The mass was then removed in two pieces and sent in specimen cups for further evaluation by the Department of Pathology. The surgical site was then flushed with copious amounts of sterile normal saline and a routine layered closure was performed.

Pathology Report:

 “BIZARRE PAROSTEAL OSTEOCHONDROMATOUS PROLIFERATION.” No malignancy seen.

Discussion: Bizarre parosteal osteochondromatous proliferation (BPOP) is a rarely occurring reactive process that may resemble a tumor. It develops most often in the hands and feet of adults in their 20’s to 30’s affecting males and females equally. It is a well-circumscribed lesion which is usually touching an underlying bone.

CT scan can be helpful in distinguishing these lesions from osteochondromas. A CT scan will reveal a cortex and medullary cavity of the bone that is continuous with the cortex and medullary cavity of the osteochondroma. In BPOP, the lesion is not continuous with the underlying bone. Gross pathology of BPOP has been described as a nodular surface covered with glistening cartilage with the bony aspect of the lesion having a distinct blue tint.

This lesion, although benign, does display aggressive features on radiographic and histological examinations. This leads to difficulty in establishing the correct diagnosis with a differential including osteochondroma, myositis ossificans and a low or high grade surface osteosarcoma. BPOP may recur in as many as 50% of all cases as early as two months to two years after surgery. However, recurrences can simply be managed with re-excisions.

The 19 year old patient described in the case above was placed in a posterior splint after surgery and confirmed compliance of non-weight bearing with the use of crutches. He was graduated to a post-op shoe approximately 2 weeks later. He had an uneventful post-op course and at his most recent office visit he displayed no signs of a recurrence of the lesion.

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