What is the appropriate management for a patient with a suspected acanthoma, considering potential benign or malignant nature?

Management of Acanthoma

For a patient with a suspected acanthoma, perform a biopsy for histologic confirmation to distinguish benign acanthoma from malignant lesions, then proceed with excision or cryosurgery based on the pathology results. 1, 2

Diagnostic Approach

The term "acanthoma" encompasses various benign epidermal keratinocyte tumors, but clinical diagnosis alone is insufficient because these lesions can mimic malignant conditions. 3

Key Clinical Features to Assess

• Location and sun exposure history: Acanthomas on chronically sun-exposed skin (scalp, face, dorsal hands) raise concern for actinic keratosis or squamous cell carcinoma (SCC) rather than simple benign acanthoma 1
• Lesion characteristics requiring immediate concern:
  • Bleeding 1, 4
  • Pain 1, 4
  • Thickened texture when palpated between fingers 1
  • Rapid growth 4
  • Failure to respond to standard treatment 5, 4

Biopsy Indications

Obtain histologic confirmation when uncertainty exists in distinguishing acanthomas from superficial basal cell carcinoma, SCC in situ, invasive SCC, or amelanotic melanoma. 1 The clinical and histopathological similarities between benign acanthomas and well-differentiated SCC make definitive differentiation difficult or impossible without biopsy. 6

Pathologic evaluation should ideally be performed by a dermatologist or pathologist experienced in interpreting cutaneous neoplasms for accurate clinicopathologic correlation. 1

Treatment Based on Histologic Diagnosis

For Confirmed Benign Acanthoma

• Cryosurgery with liquid nitrogen is an effective first-line treatment for benign lesions including trichilemmal keratosis 2, 4
• Curettage is rated as the best treatment option for hypertrophic lesions 5
• Avoid curettage in areas with terminal hair growth due to risk of incomplete removal of follicular extension 5

For Lesions with Malignant Features

If histology reveals atypical features (tumor necrosis, marked cytologic atypia, numerous mitoses including atypical forms), treat as malignant: 7

• Wide local excision with 3-5 mm margins for trichilemmal carcinoma or malignant transformation 2
• Standard surgical excision for confirmed SCC 1
• Refer to skin cancer multidisciplinary team when invasive malignancy is in the differential 1

Referral Pathways

Urgent 2-Week Cancer Pathway Referral Required For:

• Bleeding lesions 4
• Painful lesions 4
• Thickened lesions with substance 1, 4
• Suspicion of invasive SCC 1, 4

Routine Dermatology Referral For:

• Treatment failure with standard therapies 1, 4
• Multiple or relapsing lesions 1, 4
• Long-term immunosuppressed patients 1, 4

Primary Care Management Appropriate For:

• Biopsy-confirmed benign acanthoma with simple presentation 4
• Non-immunosuppressed patients 4
• Lesions responding to standard first-line treatments 4

Critical Pitfalls to Avoid

Never assume clinical diagnosis alone is sufficient. Melanoacanthomas and other acanthoma variants can mimic malignant lesions, and atypical presentations occur that delay correct diagnosis. 7 Failure to obtain histology on treatment-resistant lesions may miss invasive SCC. 5

Do not treat field changes with focal destructive therapy alone. Curettage addresses focal lesions but does not treat the field of actinic damage if present. 5

Patient Education

Educate patients that acanthomas on sun-exposed skin may be part of chronic actinic damage requiring ongoing monitoring. 4 Advise patients to self-monitor for new bleeding, pain, or rapid growth and return promptly for evaluation. 4 Sun protection counseling is essential for all patients with lesions on chronically sun-exposed sites. 1, 4