Interdigital neuroma (Morton's neuroma) most commonly occurs between which metatarsal spaces, and what is the histological finding?
- A 3rd–4th web space (most common); perineural fibrosis with endoneural sclerosis — not a true neuroma ✓
- B 1st–2nd web space; perineural fibrosis with Schwann cell proliferation
- C 2nd–3rd web space; true schwannoma with nuclear palisading
- D 4th–5th web space; ganglion cyst compressing the nerve
Correct answer: A. 3rd–4th web space (most common); perineural fibrosis with endoneural sclerosis — not a true neuroma
Explanation
Morton's neuroma is a non-neoplastic perineural fibrosis (pseudoneuroma) of the common digital plantar nerve, most commonly in the 3rd webspace (between 3rd and 4th metatarsal heads), followed by the 2nd webspace. Histologically, there is perineural and endoneural fibrosis, hyalinization of vessel walls, and nerve degeneration — no Schwann cell neoplasia. Mulder's sign (click with transverse metatarsal compression and web space pressure) is pathognomonic. Treatment is injection, wide-toe box footwear, or surgical excision via a dorsal approach (preserves plantar sensation).
Reference: Maheshwari Essential Orthopaedics, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.