Skin lesions Flashcards
(36 cards)
Which type of skin cancer is more prevalent on the hand: basal cell carcinoma (BCC) or squamous cell carcinoma (SCC)?
Squamous cell carcinoma (SCC) is more prevalent, comprising approximately 70% of hand malignancies due to chronic UV exposure, notably on the dorsal hand.
Does basal cell carcinoma (BCC) typically arise from premalignant precursor lesions?
No, BCC typically arises de novo without precursor lesions, contrasting with SCC, which often develops from actinic keratosis.
What is the most common histological subtype of basal cell carcinoma (BCC)?
The nodular (solid) subtype is most common, characterized by a pearly appearance with telangiectasias, accounting for approximately 60% of cases.
What is the primary metastatic pathway for squamous cell carcinoma (SCC) of the hand?
The primary metastatic pathway is via the lymphatic system to regional lymph nodes; hematogenous spread is uncommon.
Which genetic or phenotypic traits increase the risk of SCC on the hand?
Fair skin traits such as blue eyes and red hair increase SCC risk due to lower melanin levels, reducing UV protection.
What are poor prognostic factors for SCC of the hand?
Poor prognostic factors include location over proximal phalanges or web spaces, ulceration, diameter >20 mm, thickness >4 mm, and invasion into subcutaneous tissues or deeper structures.
What are the recommended surgical margins for excision of SCC on the hand?
A 3 mm surgical margin is generally recommended, with wider margins or even amputation indicated for aggressive lesions (>20 mm, periosteal invasion, or satellite lesions).
What is the metastatic rate of SCC located specifically on the hand?
SCC on the hand has an elevated metastatic rate of 6% to 28%, higher than the general cutaneous SCC rate of about 5%.
What makes the hand a high-risk anatomical site for developing SCC?
Frequent and cumulative UV radiation exposure makes the dorsal hand a high-risk site for SCC development.
What surgical margin is recommended for BCC excision on the hand?
A surgical margin of 2-3 mm is typically recommended for BCC, with additional excision advised if the margin is less than 0.5 mm microscopically.
When should amputation be considered for SCC on the hand?
Amputation is indicated when SCC invades periosteum, exceeds 20 mm, or when satellite lesions are present.
What reconstructive techniques are suitable following excision of skin cancers on the hand?
Options range from primary closure and local flaps for small defects to skin grafts or complex procedures like venous free flaps for larger, deeper, or functionally critical areas.
What is the recurrence rate for skin cancers of the hand treated with Mohs surgery?
The recurrence rate is approximately 1.2%, significantly lower compared to standard excision (~3%) and non-surgical treatments (~33%).
What approach is recommended for managing SCC on the hand with palpable axillary lymph nodes?
Surgical excision of the primary tumor with appropriate margins accompanied by axillary lymph node dissection is recommended.
What are the 5-year survival rates for localized versus advanced SCC?
Localized SCC has a 5-year survival of 88-92%, whereas advanced disease decreases survival to approximately 64%.
What considerations apply when performing superficial destruction techniques (curettage, cryosurgery) on the hand?
These techniques must avoid penetrating beyond the dermis into subcutaneous fat; if deeper involvement occurs, surgical excision becomes necessary.
What unique considerations exist for basal cell carcinoma (BCC) occurring on the palmar surface of the hand?
Palmar BCC is extremely rare, with fewer than 20 spontaneous cases documented outside hereditary syndromes; nodular subtype remains most common.
What virus causes verruca vulgaris on the hand?
Human papillomavirus (HPV), specifically types 1, 2, 4, and 7, infect epidermal keratinocytes causing hyperkeratotic lesions.
What percentage of verruca vulgaris lesions spontaneously regress within 2 years in immunocompetent adults?
Approximately 65-78%, typically over 6-10 months; faster regression within 3 months is uncommon (~30%).
What is the first-line topical treatment for verruca vulgaris, and its efficacy rate?
Salicylic acid solution; keratolytic action with cure rates of 50-70% after consistent use for 12 weeks.
Which skin layer is exclusively involved in verruca vulgaris?
Epidermis only, characterized by acanthosis, papillomatosis, hyperkeratosis, and parakeratosis.
Why is surgical excision typically avoided for periungual warts?
High risk (16-30%) of permanent nail deformity due to potential nail matrix injury.
Describe the histopathological features of verruca vulgaris.
Epidermal acanthosis, papillomatosis, hyperkeratosis, parakeratosis, and presence of koilocytes, without dermal invasion.
What anatomical characteristic makes superficial ablative treatments effective for verruca vulgaris?
Strict epidermal localization of HPV-infected keratinocytes; no dermal invasion necessitates deeper tissue removal.
