Squamous Cell Carcinoma
Image and content excerpted from the VisualDx clinical decision support system.
VisualDx images show variation in age, skin color, and disease stage. VisualDx has 149 images of Squamous Cell Carcinoma.
Full text and additional images for Squamous Cell Carcinoma are available in the following VisualDx packages:
C44.92 – Squamous cell carcinoma of skin, unspecified
173.92 – Squamous cell carcinoma of skin, site unspecified
SynopsisSquamous cell carcinoma (SCC) is the most common tumor of the nail apparatus. It is a low-grade malignancy that progresses slowly. SCC of the nail unit is more commonly observed in males, typically after the fifth decade. Fingernails are more commonly affected than toenails.
Predisposing factors include trauma, immune suppression, chronic bacterial or viral infection, tar, arsenic, chronic radiation exposure, radiation therapy, or inherited dermatologic disorders such as ectodermal dysplasia, dyskeratosis congenita, or dystrophic epidermolysis bullosa.
SCC of the distal digit typically begins in the lateral nail folds or distal groove and invades the nail unit by extension; nevertheless, SCC may occasionally arise in the nail bed. The early appearance may mimic that of more benign conditions such as verruca, chronic paronychia, or infection.
A diagnostic biopsy is often delayed due to the slow progression of disease, patient reluctance to undergo biopsy, technical difficulties, or prolonged treatment of a suspected benign condition. The histology is typically well differentiated and may appear entirely in situ (Bowen's disease). However, as long-standing Bowen's disease frequently shows evidence of microinvasion on serial histologic cuts, it is typically treated as aggressively as invasive SCC.
Neglected lesions may spread to the adjacent bone, but metastasis is rare.