What is the most likely diagnosis for an elderly man with a painless, non-bleeding, 2.5 cm flesh-colored skin lesion on his arm, with features on the nose, and no other symptoms, after a biopsy is performed?

Basal Cell Carcinoma

The most likely diagnosis is basal cell carcinoma (BCC), given the presentation of a painless, non-bleeding, 2.5 cm flesh-colored lesion in an elderly patient on a sun-exposed area. 1

Clinical Reasoning

Why Basal Cell Carcinoma is Most Likely

• BCC is the most commonly diagnosed skin cancer, accounting for the majority of skin cancer cases, and typically presents as a flesh-colored or pearly papule with characteristic features on sun-exposed areas like the nose and arms 1

• The clinical presentation matches classic BCC features: painless, slow-growing, flesh-colored lesion with a size of 2.5 cm, and the mention of "features on the nose" suggests the characteristic pearly appearance with telangiectasias that define nodular BCC 2, 3

• BCC rarely bleeds spontaneously unless traumatized, which aligns with the patient's report that the lesion does not bleed 2, 4

• The elderly demographic is the highest risk group for BCC, particularly fair-skinned individuals over 65 years with sun exposure history 1

Why Other Diagnoses are Less Likely

• Actinic keratosis typically presents as rough, scaly patches rather than a 2.5 cm flesh-colored lesion, and would be expected to have a hyperkeratotic surface 5

• Squamous cell carcinoma (SCC) more commonly appears as a firm, hyperkeratotic papule or plaque with central ulceration, not a flesh-colored non-bleeding lesion 3, 4

• Melanoma would be expected to show pigmentation and meet ABCDE criteria (asymmetry, border irregularity, color variability, diameter >6mm, evolution), which is not described in this flesh-colored lesion 1

Critical Management Steps

Biopsy Technique is Non-Negotiable

• Complete excision with a scalpel and 2 mm margins is the standard practice for any suspected malignant cutaneous lesion, not partial biopsy, as complete histologic assessment is necessary 1, 6

• Never use destructive techniques (cryotherapy, laser, electrocautery) without histological confirmation, as tissue destruction eliminates the ability to perform histopathological examination and represents a significant deviation from standard of care 7, 8

• All excised tissue must be sent for histopathological examination to confirm diagnosis, assess margins, and determine if further treatment is needed 1

What the Pathology Report Must Include

• Diagnosis confirmation of the lesion type (BCC subtype if confirmed) 1, 6

• Assessment of margin clearance to determine if re-excision is necessary 1, 6

• Presence of high-risk features including aggressive histologic patterns, perineural invasion, or ill-defined borders that would affect treatment planning 3, 4

Definitive Treatment After Biopsy Confirmation

If BCC is Confirmed

• Surgical excision is the gold standard for most BCCs, with cure rates exceeding 95% for primary lesions 2, 9

• Mohs micrographic surgery has the lowest recurrence rate (less than 1% for primary BCC) but is best reserved for large tumors, high-risk histologic subtypes, or tumors in cosmetically sensitive areas like the nose 3, 4

• For this 2.5 cm lesion, standard surgical excision with 4-6 mm margins would be appropriate if low-risk features are present, or Mohs surgery if high-risk features or location on the nose requires tissue conservation 2, 3

Alternative Treatments (Less Preferred for This Size)

• Electrodesiccation and curettage or cryotherapy are options only for small (<1 cm), low-risk, superficial BCCs, not appropriate for a 2.5 cm lesion 9, 4

• Topical imiquimod or fluorouracil are reserved for superficial BCC only and would not be appropriate for a 2.5 cm nodular lesion 3, 4

Follow-Up Surveillance

• The five-year risk of subsequent skin cancer after one BCC is 41%, increasing to 82% after more than one diagnosis, making regular surveillance essential 3

• Physical examinations every 3-6 months for 2 years, then every 6-12 months thereafter, including total body skin examination and regional lymph node assessment 1

• Patient education about sun protection and self-examination for new or changing lesions is critical for secondary prevention 1

Common Pitfalls to Avoid

• Do not assume benignity based on lack of bleeding or pain – BCC is characteristically painless and non-bleeding until advanced 2

• Do not perform partial biopsy or use destructive techniques without complete excision, as this compromises diagnosis and staging 7, 8

• Do not delay excision – even though BCC rarely metastasizes, it is locally invasive and can be destructive if left untreated 2