Hyperplastic areas in the Zymbal's gland are characterized by a focal increase in the number and often the size of the sebaceous acini, often with slight distortion of the lobular architecture and slight compression of the adjacent tissue. They are composed of variably sized acini lined by relatively well-differentiated epithelial cells with enlarged nuclei and cytoplasm that is more basophilic and less foamy than in normal cells. The normal maturation sequence of the acinar cells may be obscured or absent. Hyperplasia lacks the pronounced cellular atypia, marked architectural distortion, and invasion of adjacent tissue, which are features of neoplastic lesions. Hyperplasia may be a reactive change secondary to inflammation or degeneration. Hyperplasia occurring in the absence of concurrent degeneration or inflammation is considered a preneoplastic lesion and an early-stage change in the morphologic continuum from hyperplasia to carcinoma.
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