Acinic cell carcinoma overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Swathi Venkatesan, M.B.B.S.[2]
Overview
Acinic cell carcinoma (ACC) is a low-grade malignant salivary neoplasm that constitutes approximately 17% of primary salivary gland malignancies. In the head and neck region, the parotid gland is the predominant site of origin. This tumor is usually a low-grade, highly differentiated carcinoma. Women are usually more frequently diagnosed than men. There are many risk factors, including cigarette smoking, genetic predisposition, radioactive substances, viral infections, rubber manufacturing, plumbing equipment and some types of woodworking, as well as asbestos mining and exposure to nickel compounds. Patients typically present with a slowly enlarging mass in the parotid region, nausea, vomiting and digestion problems. Treatments include complete surgical resection, chemotherapy, and radiation therapy. [1]
Historical Perspective
- ACC was referred to as an entity for the first time more than 50 years ago by Godwin et al
- The “acinar” term is derived from Latin term “acinus”, which means a cluster of and looks like grapes branch
- The histological appearance is quite similar to secretory parenchymatous cells.
- Before discovering this disease, clinically Acinic Cell Carcinoma was unrecognized.
- At the time after recognizing the disease, it thought to be the nature of the tumor is benign.
- Afterward, it has been detected that the recurrence tendency of the tumor showed the possibility of the malignant nature of the tumor.
- Later WHO (World Health Organization) re-classified as a “malignant carcinoma” with low-grade behavior.
Pathophysiology
ACCs usually present as solitary, encapsulated, soft tumors of a grey-white color. In recurrent lesions, the tumor often appears lobulated, the capsule may be absent, and areas of necrosis may be evident. ACC is histologically defined by serous acinar cell differentiation. However, several cell types and growth patterns are recognized.
Microscopic Pathology
- Tumor shows multidirectional differentiation towards acinar, ductal as well as myoepithelial elements
- Variable patterns: solid, microcystic, papillary cystic (associated with hemorrhage), follicular
- Variable cell types: uniform acinar (serous) type cells with basophilic granular cytoplasm, clear cells (hypernephroid pattern, contains glycogen or mucin), vacuolated, intercalated duct, nonspecific glandular cells (smaller, syncytial)
- Cytologic features of acinic cell carcinoma on fine needle aspiration:
- Chromatin stippled.
- Granular cytoplasm.
- Sheets of cells/acinar formation.
Differential diagnosis
Acinic cell carcinoma should be differentiated from:
- Parotitis
- Parotid gland benign tumor
- Thyroid Carcinoma [2]
- Adenocarcinoma
- Mucoepidermoid carcinoma
- Pleomorphic adenoma
- Warthin tumor
- Adenoid cystic carcinoma
- Sebaceous lymphadenoma
- Benign lymphoepithelial lesion
- Sialadenosis
- Radiation-induced sialadenitis
Epidemiology and demographics
Acinic cell carcinoma can appear at any age however, it is common in children.
- Acinic cell carcinoma appears in all age groups, but presents at a younger median age (approximately 52 years) than most other salivary gland cancers.
- Women are more frequently diagnosed than men.
- Occurrences in children are quite common.
- According to the National Cancer Data Base Report on cancer of the head and neck in the United States, the parotid gland was the predominant site of origin (86.3%) for reported acinic cell carcinoma.
- Regional and distant metastasis, high grade, and large tumor size were all more common among patients older than 30.
- No ethnic or racial predilection showed an association with acinic cell carcinoma.
Risk factors
Radiation exposure and positive family history are known risk factors for acinic cell carcinoma. Clinical data has suggested that the development of acinic cell carcinoma is related to several factors.
- Radiation exposure: Radiation treatment for the head and neck cancer increases the risk of developing salivary gland cancer. Workplace exposure to certain radioactive substances may also increase the risk of salivary gland cancer. [3]
- Therapeutic radiation of the head and neck region
- Positive family history: familial predisposition
- Strong association between Epstein Barr Virus and lymphoepithelial carcinomas
- Endogenous hormones: Estrogen receptors, progesterone receptors and androgen receptors
- Iodine treatment of thyroid disease
- Occupational hazards:
- Asbestos and rubber manufacturing
- Exposure to metal in the plumbing industry
- Exposure to nickel compounds
- Woodworking in the automobile industry
- Employment in hairdressing and beauty shops
Screening
Screening is not recommended for acinic cell carcinoma. Once diagnosis confirmed, ultrasonography, nuclear scans, CT scan and MRI can usually conduct for assessing the size of the tumor, location, and the nature of the tumor
Natural history, prognosis and complications
Acinic cell carcinoma is a slow growing tumor and it may affect the facial nerve or other adjacent tissues depending on its location. Prognosis is most favorable when the parotid gland is involved. Acinic cell carcinoma is a slow growing tumor and it may affect the facial nerve or other adjacent tissues depending on its location. Prognosis is most favorable when the parotid gland is involved. Progression of acinic cell carcinoma is slow but it may involve adjacent tissues if not treated adequately. Acinic cell carcinoma can spread to adjacent organs and eventually be lethal if not intervened on time. The prognosis is more favorable when the tumor is in a major salivary gland; the parotid gland is most favorable, then the submandibular gland; the least favorable primary sites are the sublingual and minor salivary glands. Large bulky tumors or high-grade tumors carry a poorer prognosis and may best be treated by surgical resection combined with postoperative radiation therapy.[4] The prognosis depends on the following:[5][6]
History and symptoms
Acinic cell carcinoma commonly presents with a mass in the neck, difficulty in swallowing and persistent pain.
Early acinic cell carcinoma does not have any symptoms. As the tumor grows larger, people may notice one or more of the following symptoms:
- A mass or lump in face, neck, or mouth area.
- Persistent pain.
- A newly noticed difference between the size and/or shape of the left and right sides of face or neck region.
- Numbness in part of face.
- New weakness of the muscles on one side of face.
- Pain and difficulty in swallowing.
Other diseases may also present with similar symptoms.
Physical Examination
Physical examination of neck may reveal a firm swelling and tenderness.
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Mastocytoma.
With permission from [7]
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Staging
Staging of acinic cell carcinoma depends on tumor size and location. In general, tumors of the major salivary glands are staged according to size, extraparenchymal extension, lymph node involvement (in parotid tumors, whether or not the facial nerve is involved), and presence of metastases. Tumors arising in the minor salivary glands are staged according to the anatomic site of origin (e.g., oral cavity and sinuses).
Clinical stage, particularly tumor size, may be the critical factor to determine the outcome of salivary gland cancer and may be more important than histologic grade. Diagnostic imaging studies may be used in staging. With excellent spatial resolution and superior soft tissue contrast, magnetic resonance imaging (MRI) offers advantages over computed tomographic scanning in the detection and localization of head and neck tumors. Overall, MRI is the preferred modality for evaluation of suspected neoplasms of the salivary glands.
Treatment
Patients with acinic cell carcinoma have many treatment options. The selection depends on the stage of the tumor. The options are surgery, radiation therapy, chemotherapy, or a combination of these methods.
- Surgery: Surgery is usually the main form of treatment for resectable salivary gland cancers.
- Radiation therapy: High-energy x-rays and other types of radiations are used to kill cancer cells from keep growing.
- Chemotherapy: The treatment is to use drugs to stop the growth of cancer cells either by killing the cells or by stopping them from dividing.
Surgery
Surgery is usually the main form of treatment for resectable salivary gland cancers.Large bulky tumors or high-grade tumors carry a poorer prognosis and may best be treated by surgical resection combined with postoperative radiation therapy.[4]
Follow-up after treatment
Complications of surgical treatment for parotid neoplasms include facial nerve dysfunction and frey syndrome, also known as gustatory flushing or auriculotemporal syndrome.[8]Frey syndrome has been successfully treated with injections of botulinum toxin A.[9],[10]
References
- ↑ Al-Zaher N, Obeid A, Al-Salam S, Al-Kayyali BS (2009). "Acinic cell carcinoma of the salivary glands: a literature review". Hematol Oncol Stem Cell Ther. 2 (1): 259–64. PMID 20063555.
- ↑ Rosero DS, Alvarez R, Gambó P, Alastuey M, Valero A, Torrecilla N; et al. (2016). "Acinic Cell Carcinoma of the Parotid Gland with Four Morphological Features". Iran J Pathol. 11 (2): 181–5. PMC 4939652. PMID 27499783.
- ↑ Al-Zaher, Nabil; Obeid, Amani; Al-Salam, Suhail; Al-Kayyali, Bassam Sulaiman (2009). "Acinic cell carcinoma of the salivary glands: A literature review". Hematology/Oncology and Stem Cell Therapy. 2 (1): 259–264. doi:10.1016/S1658-3876(09)50035-0. ISSN 1658-3876.
- ↑ 4.0 4.1 Parsons JT, Mendenhall WM, Stringer SP, Cassisi NJ, Million RR (1996). "Management of minor salivary gland carcinomas". Int J Radiat Oncol Biol Phys. 35 (3): 443–54. PMID 8655366.
- ↑ Vander Poorten VL, Balm AJ, Hilgers FJ, Tan IB, Loftus-Coll BM, Keus RB; et al. (1999). "The development of a prognostic score for patients with parotid carcinoma". Cancer. 85 (9): 2057–67. PMID 10223248.
- ↑ Terhaard CH, Lubsen H, Van der Tweel I, Hilgers FJ, Eijkenboom WM, Marres HA; et al. (2004). "Salivary gland carcinoma: independent prognostic factors for locoregional control, distant metastases, and overall survival: results of the Dutch head and neck oncology cooperative group". Head Neck. 26 (8): 681–92, discussion 692-3. doi:10.1002/hed.10400. PMID 15287035.
- ↑ Dermatology Atlas "mastocytoma" Check
|url=value (help). - ↑ Gooden E, Witterick IJ, Hacker D, Rosen IB, Freeman JL (2002). "Parotid gland tumours in 255 consecutive patients: Mount Sinai Hospital's quality assurance review". J Otolaryngol. 31 (6): 351–4. PMID 12593546.
- ↑ Naumann M, Zellner M, Toyka KV, Reiners K (1997). "Treatment of gustatory sweating with botulinum toxin". Ann Neurol. 42 (6): 973–5. doi:10.1002/ana.410420619. PMID 9403490.
- ↑ von Lindern JJ, Niederhagen B, Bergé S, Hägler G, Reich RH (2000). "Frey syndrome: treatment with type A botulinum toxin". Cancer. 89 (8): 1659–63. PMID 11042557.