Management of Target Lesion Nevus
A "target lesion nevus" most likely refers to targetoid hemosiderotic nevus (THN), a benign trauma-induced melanocytic nevus variant that requires observation only, not excision, as the purpuric halo resolves spontaneously within 2-4 weeks. 1
Clinical Recognition
THN presents with distinctive features that help differentiate it from melanoma:
- Sudden onset of a purpuric (bruise-like) halo surrounding a pre-existing nevus, typically without any apparent trigger 1
- Occurs predominantly in young females on trauma-prone skin sites 2, 1
- The central nevus persists while the ecchymotic (bruised) halo ultimately disappears 2
- No symptoms such as pain, bleeding, or rapid growth that would suggest malignancy 2
Dermoscopic Features
Dermoscopy is a useful non-invasive diagnostic tool that can help avoid unnecessary biopsy 1:
- Central nevus shows black-brown, globular or homogeneous pattern, possibly with reddish, purple, or black structureless areas and comma-shaped vessels 1
- Peripheral purpuric halo has two patterns: homogeneous reddish/purplish red areas, or an inner pale zone with outer homogeneous reddish/purplish red zone 1
Management Approach
Conservative observation is the recommended management for THN:
- No surgical intervention required beyond follow-up observation, as this is a benign lesion 1
- The purpuric halo resolves spontaneously within 2-4 weeks with rare recurrence 1
- Biopsy can be avoided when dermoscopic features are characteristic 1
When to Consider Excision
Excision should only be considered if the lesion demonstrates concerning features that suggest malignant transformation rather than THN:
- Rapid growth of the central nevus itself (not just the halo) 3
- Bleeding or ulceration not explained by minor trauma 3
- Development of firm nodules within the lesion 3
- Persistent color changes beyond the expected resolution timeframe of 2-4 weeks 1
- Pain or other symptoms that are atypical for benign nevi 3
Histopathologic Findings (If Biopsy Performed)
If excision is performed due to diagnostic uncertainty, expected findings include 2, 1:
- Intradermal or compound nevus in the central portion
- Dilated vessels with hobnail characteristics
- Extravasated erythrocytes (red blood cells outside vessels)
- Hemosiderin deposits (iron from broken-down blood)
- Possible perivascular inflammatory infiltration and fibrin deposits
Important Pitfall to Avoid
Do not mistake THN for melanoma based solely on the sudden appearance of pigmentation change 2. The key distinguishing features are:
- THN has a purpuric (bruise-like) quality to the peripheral halo, not true melanin pigmentation 2, 1
- The change is abrupt and complete (develops the targetoid appearance suddenly), whereas melanoma typically shows gradual, progressive changes 2
- The central nevus remains stable in size and characteristics 2
Patient Education
Inform patients that 1:
- The halo will fade naturally over 2-4 weeks
- Recurrence is rare
- No treatment is necessary
- They should return only if the central nevus itself changes (grows, bleeds, develops nodules)