Acinic cell carcinoma
| Acinic cell carcinoma | |
|---|---|
| Other names | Acinic cell adenocarcinoma, Acinar cell carcinoma |
| Micrograph of an acinic cell carcinoma (right of image) and acinar glands (parotid gland - left of image). H&E stain. | |
| Pronunciation |
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| Specialty | ENT surgery, Oncology, Oral and maxillofacial pathology |
| Symptoms | Slow-growing, painless mass in parotid region, occasional pain/tenderness (30-50%), facial nerve involvement (5-10%) |
| Complications | Recurrence (10-35%), metastasis (5-10%), high-grade transformation, facial nerve dysfunction |
| Usual onset | Any age; peak in 5th decade |
| Duration | Chronic |
| Types | Solid, microcystic, papillary-cystic, follicular |
| Causes | NR4A3 overexpression (80%), radiation exposure, genomic rearrangements |
| Risk factors | Prior radiation exposure, radioactive isotope exposure, certain chemical exposures, possible familial predisposition |
| Diagnostic method | Clinical examination, imaging (MRI/CT), fine needle aspiration, histopathology, immunohistochemistry |
| Differential diagnosis | Pleomorphic adenoma, Warthin tumor, mucoepidermoid carcinoma, secretory carcinoma, oncocytoma |
| Prevention | Avoiding radiation exposure |
| Treatment | Surgical resection, radiation therapy for high-risk cases |
| Medication | Chemotherapy for recurrent/metastatic disease |
| Prognosis | Excellent; 5-year survival 90-97% for localized disease; 10-year survival 88-94% |
| Frequency | 6-15% of all salivary gland malignancies; 0.13 cases per 100,000 annually |
| Deaths | Low mortality; significantly higher with high-grade transformation or distant metastasis |
Acinic cell carcinoma is a malignant epithelial neoplasm that shows differentiation toward serous acinar cells of salivary gland origin. First described by Godwin et al. in 1954, it represents approximately 6-15% of all salivary gland malignancies, making it the third most common after mucoepidermoid carcinoma and adenoid cystic carcinoma.
Approximately 80-90% of acinic cell carcinomas arise in the parotid gland, with the remainder occurring in the submandibular gland and minor salivary glands, particularly those of the buccal mucosa and palate. Rare cases have been reported in ectopic salivary gland tissue and in non-salivary sites including the breast, pancreas, and lung.
Clinically, acinic cell carcinoma typically presents as a slow-growing, painless mass. The disease has a generally favorable prognosis, with 5-year survival rates exceeding 90% for localized disease, though recurrences can develop even decades after initial treatment. While traditionally considered a low-grade malignancy, recent molecular and clinical studies have revealed significant heterogeneity, with a subset of tumors demonstrating high-grade transformation and more aggressive behavior.
Historically, acinic cell carcinoma was classified among the "adenomas" until the 1950s, when its malignant potential was recognized. The World Health Organization officially reclassified it as a malignant epithelial neoplasm in 1972, acknowledging its capacity for local invasion, recurrence, and metastasis. In 2017, the WHO classification further refined the understanding of this entity, distinguishing it from the newly described mammary analogue secretory carcinoma (MASC), which shares some morphological features but has distinct molecular characteristics.
Molecularly, acinic cell carcinoma is characterized by the overexpression of the nuclear receptor NR4A3 in approximately 80% of cases, resulting from genomic rearrangements at chromosome 9q31. Treatment typically involves complete surgical excision, with adjuvant radiation therapy reserved for cases with adverse features such as positive margins, high-grade histology, or regional metastasis.