What is the differential diagnosis and appropriate management for a small bump on my face?

Differential Diagnosis and Management of a Small Facial Bump

For any small facial bump that cannot be confidently diagnosed as benign on clinical examination, obtain a tissue diagnosis before any destructive treatment—never use cryotherapy, laser, or shave techniques on pigmented or uncertain lesions.

Initial Clinical Assessment

The differential diagnosis for a small facial bump includes:

• Benign neoplasms: Seborrheic keratosis, sebaceous hyperplasia, epidermal inclusion cyst, milia, dermatofibroma, lipoma, cherry angioma, or acrochordon 1, 2
• Premalignant lesions: Actinic keratosis (especially in sun-exposed areas in patients >60 years) 3
• Malignant lesions: Basal cell carcinoma (most common facial malignancy), squamous cell carcinoma, or melanoma (including amelanotic variants) 3, 4

Critical Warning Signs Requiring Urgent Evaluation

Any of the following features mandate excisional biopsy, not destructive treatment 4, 5:

• Change in size, shape, or color (major melanoma warning sign) 5
• Asymmetry or irregular borders 5
• Bleeding, ulceration, or crusting 4, 5
• Heterogeneous pigmentation (multiple shades of brown, black, red, or blue) 5
• Diameter >7 mm 5
• Rapid growth or recent onset 5
• Patient-reported pain, itching, or hypersensitivity 5

Physical Examination Protocol

Perform a focused examination that includes 4:

• Palpation to detect deep nodules or induration
• Measurement of lesion diameter with documentation
• Assessment of texture: smooth (sebaceous hyperplasia), rough/scaly (actinic keratosis, seborrheic keratosis), or firm (basal cell carcinoma) 3, 1
• Examination of regional lymph nodes (preauricular, cervical, submandibular) 4
• Clinical photography for baseline documentation 4

Management Algorithm

For Clearly Benign Lesions (High Confidence Diagnosis)

Seborrheic keratosis: Waxy, "stuck-on" appearance with milia-like cysts on dermoscopy—observe or treat with cryotherapy/shave excision for cosmetic concerns 1, 2, 6

Sebaceous hyperplasia: Soft, pale yellow bumps with central dell on forehead/cheeks—no treatment required unless cosmetic, then laser or electrodesiccation 1

Milia: 1-4 mm white keratinous cysts—simple deroofing with needle or refer to dermatology if multiple/eruptive 7

Epidermal inclusion cyst: Dome-shaped with central punctum—minimal excision technique (2-3 mm incision, express contents, extract cyst wall) 8

Acrochordon (skin tag): Pedunculated—scissor excision, electrodesiccation, or cryotherapy 1

For Uncertain or Suspicious Lesions

If you cannot confidently diagnose the lesion as benign, perform excisional biopsy with 2-5 mm margins using a scalpel 4, 5, 9:

• Include full-thickness skin and subcutaneous fat 5
• Send all tissue for histopathologic examination 4, 9
• Never use shave, punch, cryotherapy, or laser on uncertain lesions—these destroy tissue needed for Breslow thickness measurement if melanoma is present 4, 5, 9

For Actinic Keratosis (Rough, Scaly Lesion in Sun-Exposed Area)

Actinic keratoses are markers of chronic sun damage and carry <0.1% annual risk of transformation to squamous cell carcinoma 3:

• Biopsy is indicated if clinical uncertainty exists or if the lesion fails to respond to treatment (to exclude squamous cell carcinoma or basal cell carcinoma) 3
• Treatment options include cryotherapy, topical 5-fluorouracil, imiquimod, or photodynamic therapy 3
• Hyperkeratotic or indurated lesions warrant biopsy to exclude invasive squamous cell carcinoma 3

For Suspected Basal Cell Carcinoma

Pearly, translucent papule with telangiectasias—most common on face 3:

• Surgical excision with 4-5 mm margins is first-line for low-risk lesions 3
• Mohs micrographic surgery for high-risk facial lesions (recurrent, morpheaform subtype, or >2 cm) achieves 99% cure rate for primary BCC 3
• Curettage and cautery may be used for small, well-defined nodular BCC on trunk/extremities, but not recommended for facial lesions (33% residual tumor rate on head/neck) 3

Critical Pitfalls to Avoid

Destructive treatment without histologic diagnosis is the most common cause of melanoma-related malpractice litigation 9:

• Loss of Breslow thickness measurement prevents accurate staging and determination of surgical margins (0.5 cm for in situ vs. 2 cm for thick melanoma) 9
• Inability to assess ulceration or mitotic rate eliminates critical prognostic factors that determine need for sentinel lymph node biopsy 9
• Amelanotic melanoma can present with minimal pigmentation—any changing lesion requires biopsy regardless of color 4

If you have already performed destructive treatment on a lesion later suspected to be melanoma 9:

• Perform wide re-excision with 1-2 cm margins immediately
• Strongly consider sentinel lymph node biopsy given diagnostic uncertainty
• Refer urgently to dermatology or surgical oncology

When to Refer to Dermatology

Refer immediately for 3, 4, 5:

• Any lesion with melanoma warning signs
• Recurrent lesions after prior treatment
• Lesions requiring Mohs surgery (high-risk facial BCC)
• Multiple or rapidly growing lesions
• Diagnostic uncertainty after initial evaluation