Is a subungual hematoma the correct diagnosis for a 21‑year‑old male with a painless, blood‑filled right great‑toe nail after minor, possibly unrecognized trauma?

Subungual Hematoma: Diagnosis Confirmation

Yes, subungual hematoma is the correct diagnosis for this 21-year-old male with painless blood discoloration under the right great toenail following unrecognized minor trauma. The clinical presentation—blood-like discoloration under the nail, initial pain that resolved, absence of tenderness, swelling, or signs of infection—is entirely consistent with a simple subungual hematoma 1, 2.

Supporting Evidence for the Diagnosis

Clinical Features Match Subungual Hematoma

• Subungual hematoma is a collection of blood beneath the nail plate, typically caused by crush injury or minor trauma 1. The patient's 2-week history of blood-like discoloration fits this pattern, even without recalled trauma—unrecognized minor trauma is common 1.

• The natural history matches perfectly: initial pain for 2 days followed by resolution is characteristic, as pain relief occurs once pressure from the hematoma stabilizes 3. The painless state at presentation is expected for a 2-week-old hematoma 2, 4.

• Dermoscopic features (if examined) would show: homogeneous pattern with purple-black or red-black coloration, possible globular patterns, and peripheral fading—all typical of subungual hematoma rather than melanoma 2, 4.

Key Differentiating Features from Other Diagnoses

The absence of concerning features effectively rules out melanoma:

• No Hutchinson sign (pigmentation extending to proximal nail fold) 2
• No longitudinal irregular bands or triangular-shaped bands 2
• Homogeneous appearance rather than irregular pigmentation 2, 4
• Critically, observation for distal progression of the discoloration over weeks confirms benign hematoma 4

Infection is appropriately excluded based on:

• No nail fold swelling, erythema, or warmth 5
• No signs of paronychia 5
• Non-tender examination 5

Fracture is correctly ruled out given:

• No point tenderness over the distal phalanx 3
• No swelling or bruising 3
• Normal ambulation without pain 3

Management Appropriateness

The Conservative Approach is Correct

Your "watch and wait" strategy is evidence-based and appropriate 3:

• Nail trephination is NOT indicated at 2 weeks post-injury when pain has already resolved 3. Trephination provides pain relief by releasing pressure, but this patient is already pain-free 3.

• Nail removal with suture repair is unnecessary regardless of hematoma size, as studies show no complications (infection, osteomyelitis, or major nail deformities) occur with observation alone 3.

• Expected timeline: The nail will grow out over approximately 4 months (range 1.5–11 months), carrying the discolored blood distally until it reaches the free edge 3.

Critical Monitoring Instructions

Your return precautions are appropriate but should specifically include 5, 6:

• Signs of infection: warmth, increasing redness, purulent drainage, or fever 5
• Development of paronychia: swelling or tenderness of the proximal or lateral nail folds 5
• Persistent or worsening pain beyond what's expected 3
• Failure of the discoloration to progress distally over 4–6 weeks, which would raise concern for melanoma rather than hematoma 4

One Critical Caveat

If the pigmentation does NOT move distally with nail growth over the next 4–6 weeks, urgent dermatology referral is mandatory 7, 4. Stationary pigmentation suggests melanocytic lesion (melanoma or nevus) rather than hematoma 7, 4. This is the single most important follow-up instruction to emphasize to the patient 4.

Documentation Strengths

Your documentation appropriately includes:

• Detailed history with timeline 5
• Thorough physical examination excluding alternative diagnoses 5
• Clear reasoning for diagnosis 2
• Appropriate safety-netting with return precautions 3

The only addition needed: Explicitly document that you advised the patient to return if the discoloration does not progress toward the distal nail edge over the next 4–6 weeks 4.