Squamous Cell Carcinomat

Squamous cell carcinoma (SCC) is a true invasive carcinoma of the surface epidermis. It affects people over 50 years of age with fair skin, blue eyes, blond hair, >3 and poor tanning ability. Contributing factors include chronic solar damage, ionizing radiation, chronic wounds or ulcers, human papilloma virus infection (serotypes 5, 8, 16 and 18), exposure to chemical carcinogens (arsenic, polycyclic aromatic hydrocarbons, and topical nitrogen mustard), immunosuppression (patients who

Figure 22 Multiple keratotic lesions on the hand of a patient who underwent renal transplantation. Some lesions correspond to hypertrophic actinic keratoses but others have evolved towards invasive squamous cell carcinoma.

have received transplants), chronic inflammatory disorders (epidermolysis bullosa), and genetic syndromes characterized by poor DNA repair mechanisms (xeroderma pigmentosum) (99). The highest incidences are reported from Texas and Queensland, Australia (100).

SCC arises de novo in sun-damaged skin or from precursor lesions such as actinic keratoses (Fig. 22). The latter are erythematous, scaly, or keratotic papules of sun-exposed skin of the face, neck, arms and hands, and carry a collective 20% overall risk of malignant transformation (101).

Bowen's disease presents as erythematous scaly patches of variable size (Fig. 23). It resembles tinea, psoriasis, eczema, or superficial BCC (102). The lesions enlarge slowly over time, are asymptomatic or slightly pruritic, and affect glabrous skin. Some cases evolve into invasive SCC. Human papilloma viruses (HPV) 16, 18, 31, 32, 39, 51, 52, 53, 54 are of causative importance (103). The relationship with -g visceral neoplasia is controversial and probably related to arsenic ingestion.

Queyrat's erythroplasia is identical to Bowen's disease but located on the glans penis. Approximately 40% of cases develop invasive SCC.

Invasive SCC presents as an indurated nodule of variable size. The surface may d be keratotic, ulcerated, or exophytic (Fig. 24). Most commonly, the lesions affect the head and neck or extremities (104). The lower lip is a frequent site in smokers, with |

95% of cases occurring in men.

Verrucous carcinoma (105) is a variety of SCC with low metastatic potential. Lesions appear clinically as are exophytic (cauliflower-like), asymptomatic, and

Diagram 1 Mohs' Surgery Procedure. A. A map is drawn depicting the anatomical location and approximate size of the tumor. Debulking is then performed under local anesthesia using a small curette. B. The resultant debulked defect and any area suspicious for tumor is excised using 2-3 mm margins. The incision is made at a 30-45-degree angle to create a disk-like specimen that will allow easier processing of the lateral margins. Identifying marks such as skin nicks are made on the patient and specimen to identify proper orientation. C. The specimen is divided and each section is properly marked on the diagram. D. Sections are color-coded with ink, embedded in a chuck with embedding medium, and quick frozen in liquid nitrogen. The blocks are then sectioned at 4-10 mm in the cryostat, starting from the deepest portion of the specimen and with the deepest margin at the same level than the lateral epidermal borders.

slowly growing. There are three types depending on location: florid oral papillomatosis, carcinoma cuniculatum of the foot, and Buschke-Lowenstein tumor of the genitalia. Histological examination shows variable degrees of keratinocytic atypia (nuclear enlargement, hyperchromatism, prominent nucleoli, increased nuclear-cytoplasm ratio, abnormal intra- or extracellular keratin production) (106). Bowen's disease and Queyrat's erythroplasia are in situ carcinomas with full-thickness keratinocytic atypia and frequent mitotic figures. The loss of polarity gives the epidermis a characteristic windblown appearance (107). In invasive SCC, the bands of atypical cells penetrate the dermis and there are variable atypical mitoses.

Four grades of severity are recognized for SCC according to the proportion of differentiated cells present in the tumor (Broders' classification). In this system, differentiation equals keratinization (108,109). In grade 1, more than 75% of cells are differentiated (multiple horn pearls); in grade 2, more than 50% (several horn pearls); in grade 3, more than 25% (many atypical cells, horn pearls absent); and in grade 4, less than 25% (only spindle cells).

Verrucous carcinoma (110) shows a proliferation of well-differentiated kerati-nocytes with minimal atypia and a bulbous pushing base that is characteristic. There is epidermal hyperplasia, papillomatosis, and hyperkeratosis.

How To Reduce Acne Scarring

How To Reduce Acne Scarring

Acne is a name that is famous in its own right, but for all of the wrong reasons. Most teenagers know, and dread, the very word, as it so prevalently wrecks havoc on their faces throughout their adolescent years.

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