Pathology of Squamous Cell Carcinoma

Study Notes

Neoplasia: abnormal mass of tissue that grows excessively and uncoordinated with normal tissue, persists after cessation of stimulus.
Difference between neoplasia and hyperplasia: neoplasia arises spontaneously, hyperplasia arises by stimulus.

Characteristics: well-differentiated epithelium, little or no cytological atypia, rare mitoses, intact basement membrane.
Adjacent connective tissue: heavily infiltrated by chronic inflammatory cells.

Definition: rare variant of high-grade SCC, characterized by dysplastic surface epithelium and invasive spindle cell element.
Etiology: often develops as a recurrence after radiotherapy for a more differentiated SCC (dedifferentiation).
Clinical features:
- Age: old age
- Sex: no sex predilection
- Site: predominantly in upper aerodigestive tract (larynx, oral cavity, esophagus)
- Shape: pedunculated or sessile nodular mass, fungating mass, or ulcer
- Features: rapid growth, invasion of bone and underlying tissues, pain and paresthesia
Histopathologic features:
- Anaplastic spindle-shaped epithelial cells with signs of malignancy (hyperchromatism, pleomorphism, increased N/C ratio, increased mitotic activity, and abnormal mitotic figures)

Three types according to degree of differentiation of invading cells:
- Well-differentiated: neoplastic epithelium consists of masses of prickle cells with a limiting layer of basal cells and basement membrane
- Moderately differentiated: keratin pearls sparse or absent, prickle cells and nuclei more pleomorphic, mitotic activity abundant
- Poorly differentiated anaplastic tumors: epithelial cells irregular, no nests or keratin pearls, variable lymphocytic and plasma cell infiltration in stroma