CASE REPORT

Intermetatarsal rheumatoid node with Morton's neuroma signs - differential diagnosis

Dr. Antonio Carlos Flores dos Santos

Orthopaedist Traumatologist

Correspondence

SUMMARY

A 38 years old female pacient, in treatment by rheumatoid arthritis (RA), with pain in the 3º intermetatarsal space and paresthesia in the 3º toe, bilateral. She was operated for resection of hipoechoicsmasses showed in echographic examination. The anatomopathologic diagnosis was fibrinoid and mixoid degeneration ( rheumatoid nodule.

Keywords: Morton's neuroma,Rheumatoid nodule, Interdigital nodule.

INTRODUCTION

A female patient, 38 years old, university student presented RA without defined articular deformities. She reported pain in distal region of the intermetatarsal third space of both feet. Initially insidious, the pain wasn't related to any past trauma and it presented an evolution to paresthesia in the interdigital third space and in the third and fourth toes extremities of both feet, but clearly in the right one.

The control examination of RA, requested and evaluated by the rheumatologist, showed a disease in the latency stage of signs and symptoms. Methotrexate was being administrated. (Fig 1).

The XR examination of feet didn't show osteoarticular changes (Fig 2)

The echography of forefeet (Figure 3) showed an hypoechoic mass in distal intermetatarsal third space region of both forefeet.

The patient underwent surgical treatment and the large nodes (larger in the right foot) were resected from descripted regions without intercurrent events during the surgery. (Fig. 4)

The anatomicopathological examination described a chronicle tenosynovites with fibrosis, granulation and fibrinoid and myxoid degeneration (rheumatoid node).

The postoperative didn't present any complications and the remission of the symptoms occurred in approximately four weeks.

DISCUSSION

Dedrich⁽⁴⁾ and Cracchiolo^(1,2,3) refer to RA signs and symptoms in interdigital space as usually originated from intermetatarsal bursitis, simulating Morton's neuroma pathology (pain and toes paresthesia).

The classical finds in RA in the forefoot are the hallux valgus with a high degenerative articular implication and synovitis of metatarsophalangeal articulations of little toes, and irreducible dorsal dislocation. These are the early signs of RA that evolve to metatarsalgia by compression of the heads of metatarsal in the fatty pad of the forefoot against the floor⁽³⁾.. Large bursas can be found in distal intermetatarsal spaces and occasionally under the hallux⁽¹⁾.

The interdigital neuroma (Morton's neuroma) ⁽⁷⁾ is a compression of the interdigital nervous ramus in the distal intermetatarsal portion, between the heads and the transversalis intermetatarsal ligament. It usually represents an increase of the perineural tissue with fibroblastic proliferation. It is more frequent in the third space due to anatomic characteristic of the nervous distribution of intermetatarsal ramus of medial and lateral plantar NN. It prevails among women and it is usually unilateral⁽⁵⁾.

The diagnosis is clinical through the physical examination verifying the pain by the digital pressure of the sick intermetatarsal space. It is not palpable as a differentiated structure. ⁽⁶⁾ In case of positive palpation of individual tissue mass in this particular region, it doesn't mean a Morton's neuroma diagnosis and so a differential diagnosis should be searched,

REFERÊNCIAS BIBLIOGRÁFICAS

1- Dedrich, D.K.,et al,Rheumatoid arthritis presenting as spreading of the toes. JBJS 72 A (3),463-464, 1990.         [ Links ]

2- A. Cracchiolo III Rheumatoid arthritis of the Foot & Ankle, F&A Manual, G Sanmarco, 207-209,1998.         [ Links ]

3- Cracchiolo, A. Surgery for rheumatoid deseases.AAOS instructive course lecture. Mosby Times Mirror, 33: 386. 1984.         [ Links ]

4- Cracchiolo A. et alArthroplasty of the first metatarsophalangeal joint with a doble stent silicone implant. JBJS 74A,552-563,1992.        [ Links ]

5- Morton, T.G. A peculiar and painful affection of the fourth metatarsalphalangeal articulation. Am. J. Med.Sci..71:37. 1876.        [ Links ]

6- Mann,R.A.and Reynolds,J.D.,Interdigital neuroma. A critical analysis.F&A 3, 238.1983.         [ Links ]

7- Mann,R.A.,Deseases of the nerves of the foot, in Mann,R.A. Surgery of the foot 5^th ed. St.Louis, Mosby, 1986, pp 199-208.         [ Links ]

Correspondence to
Rua Prof. Annes Dias, 154,cj. 803
CEP 90020-090
P.Alegre,RS
Email: dracfs@terra.com.br

Trabalho recebido em 25/04/2003.
Aprovado em 23/10/2003

Work Performed : Clínical Private