A Case of a Second Intermetatarsal Space Gouty Tophus with a Presentation Similar to a Morton's Neuroma.

Fatemeh Razaghi,Ashish Shah,Kyle Paul,Alan Hsu,Matthew Anderson,Jeffery A Jones,Carly A Cignetti,Eva Lehtonen,Eildar Abyar,John L Johnson

doi:10.7759/cureus.2620

Abstract

Non-infectious soft tissue lesions of the foot and ankle are relatively rare clinically. These include benign and malignant neoplasms, as well as non-neoplastic or pseudotumoral lesions such as ganglionic, synovial and epidermoid cysts, intermetatarsal and adventitious bursitis, inflammatory lesions like gouty tophi and rheumatoid nodules, Morton’s neuroma, and granuloma annulare.A 48-year-old male with a history of medically treated tophaceous gout presented with left foot neuropathic pain and paresthesia, in the setting of a well-circumscribed soft tissue lesion of the second intermetatarsal space, suspected to be a Morton’s neuroma. Magnetic resonance imaging (MRI) showed a 4.1 x 2.7 x 2.6 cm heterogeneous soft tissue mass containing multiple cystic areas. Excisional biopsy was performed and histologic examination revealed well-circumscribed nodules of amorphous material containing needle-shaped clefts, rimmed by histiocytes, and multinucleated giant cells consistent with a gouty tophus.This is the first case reported in the literature of an intermetatarsal gouty tophus causing neuropathic pain and paresthesia. While Morton’s neuroma is the most common cause of this presentation, this case illustrates that other pseudotumoral lesions, such as a gouty tophus, may present similarly, and should be considered in the differential diagnosis. While most cases of tophaceous gout can be adequately treated with urate-lowering therapy, surgery may be indicated for tophi that do not resolve with medical treatment based upon symptom severity, compression of nearby structures, and functional impairment.

Highlights

Non-infectious soft tissue lesions of the foot and ankle are relatively rare clinically
The disease naturally progresses through four phases: asymptomatic hyperuricemia, gouty arthritis, intercritical gout, and chronic tophaceous gout
The decision was made to proceed with surgery based upon diagnostic uncertainty, as well as the patient’s persistent pain and impaired quality of life, This case illustrates that while Morton’s neuroma is the most common cause of a second intermetatarsal space lesion causing neuropathic pain and paresthesia, other pseudotumoral lesions such as a gouty tophus, may present and should be considered in the differential diagnosis

Summary

Introduction

Non-infectious soft tissue lesions of the foot and ankle are relatively rare clinically. Gouty lesions most often occur in the foot at the metatarsophalangeal (MTP) or interphalangeal joints [3] This condition has been called "the great pretender", due to the wide spectrum of clinical presentations that have been described [4]. The purpose of this case report is to describe a case of a gouty tophus atypically located at second intermetatarsal web space, with a presentation similar to a Morton’s neuroma. The patient reported his pain as neuropathic and paresthetic, and radiating to the second interdigital space. There are well-circumscribed nodules of amorphous material (A1, 40X magnification), rimmed by histiocytes (B2, 200X magnification) and multinucleated giant cells, with needle-shaped clefts (B3) representing where the gout crystals were removed during processing

Discussion

Conclusions

Disclosures

Robbins SL

Terkeltaub RA