What is the diagnosis and management for a patient with multiple skin lesions resembling scars on both shoulders, without itching or pain?

Scar-like Lesions on Both Shoulders Without Symptoms

The most likely diagnosis is anetoderma, a benign condition characterized by localized areas of flaccid skin with loss of dermal elastic tissue that clinically resemble scars or herniated pouches, though lymphomatoid papulosis (LyP) should also be considered given the bilateral shoulder distribution and scar-like appearance.

Primary Differential Diagnosis

Anetoderma (Most Likely)

• Anetoderma presents as asymptomatic, soft, wrinkled patches or papules that feel like small herniated pouches when palpated, often mistaken for scars 1
• The lesions typically appear on the trunk and upper extremities (including shoulders) and are bilateral and symmetric 1
• No itching or pain is characteristic of this condition 2
• Diagnosis requires skin biopsy showing loss of elastic fibers in the dermis with otherwise normal epidermis 3

Lymphomatoid Papulosis (LyP)

• LyP can present with papulonecrotic lesions that heal with superficial scarring, creating scar-like appearances on the shoulders and trunk 4
• The condition is characterized by recurrent crops of self-healing papules and nodules that may ulcerate during regression 4
• Lesions are typically asymptomatic (no itching or pain) 4
• If cosmetically disturbing with scarring or many papulonodules, low-dose oral methotrexate (5-20 mg/week) is the most effective therapy 4

Secondary Considerations

Atrophic Lichen Planus

• Post-inflammatory hypopigmentation or atrophy from resolved lichen planus can resemble scars 5
• However, active lichen planus typically presents with violaceous, polygonal, flat-topped papules with pruritus, which is absent in this case 5
• The bilateral shoulder distribution is less typical for lichen planus 5

Morphea (Localized Scleroderma)

• Can present as indurated plaques that may have a shiny, scar-like appearance 1
• Typically progresses through inflammatory phase to sclerotic phase, eventually leaving atrophic areas 3
• Bilateral shoulder involvement is possible but less common 1

Diagnostic Algorithm

Step 1: Clinical Examination

• Palpate the lesions to assess texture: anetoderma feels soft and herniated; morphea feels indurated and bound down 1, 3
• Examine for active inflammation, erythema, or violaceous coloration that would suggest active disease rather than scar-like changes 5
• Check other body sites including trunk, arms, and legs for additional lesions 4, 1

Step 2: Obtain Skin Biopsy

• Perform punch biopsy of a representative lesion to establish definitive diagnosis 1, 3
• Request special stains for elastic fibers (Verhoeff-van Gieson stain) if anetoderma is suspected 3
• Histopathology showing CD30+ lymphocytes with papillomatosis would confirm LyP 4

Step 3: Rule Out Systemic Associations

• If LyP is confirmed, evaluate for associated lymphoproliferative disorders with complete blood count and peripheral smear 4
• If anetoderma is confirmed, screen for autoimmune conditions and antiphospholipid antibodies 1

Critical Pitfalls to Avoid

• Do not assume these are simply scars without obtaining tissue diagnosis, as LyP is a CD30+ lymphoproliferative disorder requiring monitoring for potential progression 4
• Avoid dismissing bilateral symmetric lesions as benign without biopsy, particularly given the shoulder location which is common for LyP 4
• If LyP is diagnosed, long-term follow-up is mandatory as approximately 10-20% of patients may develop associated lymphomas 4
• Do not perform excisional biopsy of all lesions if LyP is suspected, as these lesions are typically self-healing and excision is not therapeutic 4

Management Based on Diagnosis

If Anetoderma:

• No specific treatment is required as this is a benign cosmetic condition 1
• Reassurance and sun protection for affected areas 1

If Lymphomatoid Papulosis:

• Observation alone is appropriate for patients with few lesions who are not cosmetically concerned 4
• For cosmetically disturbing scarring lesions, initiate low-dose oral methotrexate 5-20 mg weekly 4
• PUVA phototherapy is an alternative for reducing lesion number 4
• Establish regular dermatologic surveillance for potential lymphoma development 4