After a long drive I have dorsal foot swelling, erythema of the second toe on pressure, pain walking barefoot, a pebble‑like sensation under the second metatarsal head, a small interspace callus, and occasional ankle edema—what is the likely diagnosis and how should I manage it?

Likely Diagnosis: Morton's Neuroma with Metatarsalgia and Possible Early Diabetic Foot Complications

You most likely have Morton's neuroma (interdigital neuroma) causing the "pebble-like" sensation under your second metatarsal head, combined with metatarsalgia from increased plantar pressure evidenced by your interspace callus. The dorsal swelling, erythema with pressure, and occasional ankle edema raise concern for underlying diabetic foot complications that require urgent evaluation even if you don't have known diabetes 1, 2.

Immediate Actions Required

Rule Out Diabetes and High-Risk Conditions First

• Get screened for diabetes immediately with fasting glucose or HbA1c, as 78% of diabetic foot complications involve peripheral neuropathy, and your symptoms (altered sensation, callus formation, erythema with pressure) are classic warning signs 2.

• If you have diabetes or the screening is positive, this becomes a medical urgency requiring same-day evaluation by a foot care specialist, as the combination of swelling, erythema, and callus formation indicates high risk for tissue breakdown and ulceration 3.

• Even without diabetes, the red color change with pressure and callus between toes signals increased plantar pressure that can lead to ulceration 3.

Critical Red Flags to Exclude

Before treating this as simple neuroma, you must rule out:

• Charcot neuro-osteoarthropathy (CNO) if you have diabetes and neuropathy—the unilateral swelling, warmth, and puffiness are classic for active CNO, which if untreated leads to bone fractures, deformity, and amputation 1.

• Infection: While you don't describe purulent discharge, diabetic patients can have serious infections without fever or obvious signs 3, 4.

• Stress fracture of the second metatarsal: The "pebble" sensation and pain walking barefoot could represent a stress fracture, especially after prolonged driving in awkward foot positions 4.

Diagnostic Workup

Physical Examination Priorities

• Palpate for point tenderness along the second metatarsal shaft and head to assess for stress fracture 1.

• Perform Mulder's click test: Squeeze the metatarsal heads together while pressing up from the plantar surface between the second and third metatarsal heads—a palpable click suggests Morton's neuroma 5.

• Check protective sensation with a 10-g monofilament at the dorsal hallux and plantar metatarsal heads—loss of sensation confirms diabetic neuropathy and elevates your risk category dramatically 2.

• Assess pedal pulses (dorsalis pedis and posterior tibial) and check for claudication symptoms, as peripheral arterial disease compounds foot complications 3.

• Measure skin temperature comparing both feet—a difference ≥2°C suggests active Charcot if you have diabetes and neuropathy 1.

Imaging Studies

• Obtain weight-bearing X-rays of the foot to evaluate for stress fractures, metatarsal abnormalities, or early Charcot changes 1, 4.

• MRI is indicated if X-rays are negative but symptoms persist, especially to diagnose Morton's neuroma definitively or rule out early stress fracture or Charcot 1.

Management Algorithm

If Diabetes is Present or Suspected

1. Initiate immediate offloading with well-fitted athletic shoes with cushioned insoles—never walk barefoot 3.

2. Refer urgently to podiatry or diabetic foot clinic within 24-48 hours for comprehensive evaluation 3, 2.

3. Begin daily foot inspection looking for skin breakdown, increased warmth, or color changes 3.

4. If CNO is suspected, initiate knee-high immobilization immediately even before imaging confirmation—the consequences of delayed treatment are catastrophic 1.

If No Diabetes (After Screening)

1. Conservative management for Morton's neuroma:

   • Metatarsal pads placed just proximal to the metatarsal heads to redistribute pressure away from the neuroma 5, 6.
   • Wide toe-box shoes to reduce compression of the interspace 5.
   • Avoid walking barefoot and high heels completely 5.

2. Callus management:

   • Professional debridement by a podiatrist—do not attempt self-removal 3.
   • Toe spacers between first and second toes to reduce friction 6.

3. Address the swelling:

   • Contrary to traditional advice, do NOT elevate the foot if vascular compromise is suspected, as elevation decreases tissue oxygenation 7.
   • Keep the foot in a dependent position (lowered) if you have any signs of vascular insufficiency, as this increases blood flow 7.
   • Compression stockings may help with ankle edema if venous insufficiency is present 3.

When to Seek Urgent Care

• Any open wound or skin breakdown requires same-day evaluation 3.
• Increasing warmth, redness, or swelling suggests infection or active Charcot 3, 1.
• Fever or systemic symptoms mandate immediate emergency evaluation 3, 4.
• No improvement after 6-8 weeks of conservative treatment warrants subspecialist referral 1.

Common Pitfalls to Avoid

• Never delay evaluation assuming this is "just" a neuroma—the combination of swelling, erythema, and callus formation in the setting of undiagnosed diabetes can rapidly progress to ulceration 3.

• Do not assume absence of pain rules out serious pathology if you have neuropathy—diabetic patients often have minimal pain despite severe tissue damage 1.

• Avoid corticosteroid injections for presumed neuroma until stress fracture is definitively excluded, as steroids near bone can impair healing 4.

• Do not rely on initial X-rays alone—stress fractures and early osteomyelitis may not be visible initially and require follow-up imaging if symptoms persist 4.

Expected Timeline

• Morton's neuroma with conservative management: 6-12 weeks for symptom improvement 5.
• Stress fracture: 6-8 weeks of protected weight-bearing 4.
• If diabetic foot ulcer develops: 6-8 weeks to heal with proper offloading, but only if vascular supply is adequate 8.

Bottom line: Get diabetes screening immediately, obtain weight-bearing foot X-rays, and see a podiatrist within one week—sooner if you have diabetes or develop any skin breakdown.