Page 406 - Concise Pathology for Exam Preparation ( PDFDrive )

14 The Oral Cavity and Gastrointestinal Tract 391

Mucinous material
Basaloid cells arranged
in a cribriform pattern

FIGURE 14.4. Adenoid cystic carcinoma showing tumour cells arranged in a cribriform
pattern around cylindrical spaces that contain mucinous material (H&E; 2003).

Acinic Cell Carcinoma

• Acinic cell carcinoma is a rare tumour that accounts for about 1% of all salivary neoplasms.
• It typically presents in the fifth decade of life, and is more common in women. Bilateral
parotid disease occurs in approximately 3% of cases.
• Most common presentation is that of an asymptomatic enlarging mass.
• Gross appearance demonstrates a mass that is well circumscribed but lacks a true capsule.
• Acinic cell carcinoma is a malignant neoplasm demonstrating serous acinar cell differentia-
tion. Acinar cells are large, polygonal with lightly basophilic, granular cytoplasm and round,
eccentric nucleus. The cytoplasmic zymogen secretory granules are PAS-positive, resistant to
diastase digestion and nonreactive or only weakly reactive to mucicarmine stain.
• This tumour is generally regarded as a low-grade malignancy. Treatment is surgical excision.
Adenocarcinoma

• Adenocarcinomas of the salivary glands are rare but aggressive tumours.
• They are most common in the parotid followed by the minor salivary glands.
• Microscopically there is formation of glandular structures, and based on the degree of
differentiation they are described as grades I, II or III tumours. Grade I lesions have
well-formed ductal structures, while Grade III lesions have a more solid growth pattern
with few glandular characteristics.
• Treatment for adenocarcinoma is aggressive. Complete local excision with facial nerve
sacrifice, partial resection of the maxilla or mandible, postoperative radiation therapy
and neck dissection is warranted in most cases.

Malignant Mixed Tumours
• Carcinoma expleomorphic adenoma is most common. It occurs when a carcinoma
develops from the epithelial component of a pre-existing pleomorphic adenoma. The
other two tumours in this category, carcinosarcoma and metastasizing mixed tumour,
are much less common.
• In a carcinosarcoma, the metastatic lesions contain both the stromal and epithelial
elements. This is different from the carcinoma expleomorphic adenoma in which
only the epithelial elements are present in metastasis. The metastasizing mixed

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