|Year : 2003 | Volume
| Issue : 1 | Page : 15-18
Acinic cell adenocarcinoma - a case report
P Sai Krishna, B Sivapathasundharam
Department of Oral Pathology, Meenakshi Ammal Dental College & Hospital, Chennai, India
P Sai Krishna
Department of Oral Pathology, Meenakshi Ammal Dental College & Hospital, Chennai
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Acinic cell adenocarcinoma is a malignant salivary gland tumour with cells that show serous acinar differentiation. Clinically if the site is the parotid gland. it may resemble a pleomorphic adenoma. Herewith we present a case of acinic cell adenocarcinoma in a 60 year old male who reported with a lobulated swelling in the parotid region, which was clinically diagnosed as pleomorphic adenoma or carcinoma ex-pleomorphic adenoma and histologically diagnosed as acinic cell adenocarcinoma.
Keywords: Adenocarcinoma, acinic cell carcinoma, acinous cell carcinoma
|How to cite this article:|
Krishna P S, Sivapathasundharam B. Acinic cell adenocarcinoma - a case report. J Oral Maxillofac Pathol 2003;7:15-8
|How to cite this URL:|
Krishna P S, Sivapathasundharam B. Acinic cell adenocarcinoma - a case report. J Oral Maxillofac Pathol [serial online] 2003 [cited 2021 May 7];7:15-8. Available from: https://www.jomfp.in/text.asp?2003/7/1/15/41000
| Introduction|| |
Acinic cell adenocarcinoma (ACC) is a malignant salivary gland tumour with cells showing serous acinar ditlcrcntiation  . This tumour was first recognized by Nasse 110 years back who described 4 parotid adenomas that closely resembled normal acinar cells  .
This tumour closely resembles pleomorphic adenoma in gross appearance, tending to be encapsulated and lobulaled  . ACC occurs chiefly in the parotid and occasionally in other major salivary glands and in the accessory intraoral glands with common age range of 38-46 years ,,
The multi-directional differentiation toward acinar ductal and myo-epithelial elements has been studied by several authors ,,. We herewith present a case of ACC arising from the parotid gland consisting of all the morphological growth patterns with predominant serous cell differentiation and mixed cellularity.
| Case Report|| |
A 60-year-old male patient reported with a complaint of swelling on the left side of the face, which was present for the past 10 years. Initially it started as a small nodule and began to increase in size in the 4 years. There had been rapid increase in size of the lesion since the last 4 months.
The swelling was firm and nodular measuring about 6 cm X 5.5 cm extending from the tragus of the ear to the angle of the mandible. The swelling was overlapping the anterior margin of sternocleidomastoid muscle. Ear lobule on the left side was elevated. Difficulty in closing the left eye and deviation of the lip to the right side indicating facial nerve involvement were noticed.
A provisional diagnosis of pleomorphic adenoma was made and carcinoma ex-pleomorphic adenoma was considered in the differential diagnosis in view of the recent increase in the rate of growth. Incisional biopsy was done.
| Histopathology|| |
Biopsied sections revealed cells with basophilic cytoplasm and acinar differentiation. Few acinar cells appeared granular [Figure 1]. Some areas showed clumps of cells with vacuolated cytoplasm containing spherical nuclei [Figure 2]. There were intercalated duct-like cells, many of which had formed ducts with basophilic material within the lumen [Figure 3]. One area showed cystic degeneration with papillary projections within the cystic space[Figure 4]. These features were consistent with ACC. The tumour was excised and the patient recovered uneventfully. There has been no recurrence of the tumour till date.
| Discussion|| |
ACC is defined as a primary glandular neoplasm demonstrating differentiation toward the terminal intercalated ductal acinar (intercalated) unit and exhibiting one or more of histologic patterns 13 [Figure 1],[Figure 2],[Figure 3],[Figure 4].
The parotid is the most common primary site involved in upto 90 of cases , ,followed by the minor salivary glands , . ACC accounts for 7% to 17.5% of malignant salivary gland tumours[ 16],, . The reported age range for patients with ACC is 3 to 91 years and the female to male ratio is approximately 2:1. The average age range of diagnosis is 38 to 46 years, which is a decade younger than patients with other parotid malignancies. ACC is the second most common salivary gland neoplasm occurring in childhood after Warthin's tumor and pleomorphic adenoma and the third most common bilateral salivary gland tumor  .
Gross pathologic specimen of ACC appears as an intraparenchymal circumscribed tangrey rubbery mass, with diameter ranging from 3cm to 22 cm  .Recurrent tumors are characterized by multi-nodular appearance. De -differentiated ACC presents a bosselated appearance with ill-defined borders, which infiltrates adjacent soft tissue and bone  .
ACCs arise in different morphologic growth patterns like solid or classic, microcystic, follicular and papillary cystic  . A mixture of patterns are very common as seen in our case while observing different fields[Figure 1],[Figure 2],[Figure 3],[Figure 4].
Solid or classic pattern is composed of well differentiated acinar cells with prominent basophilic to grey granularity of their cytoplasm  . The individual cells are polygonal with conspicuous cytoplasmic borders. Foci of nonspecific glandular cells with eosinophilic or amphophilic cytoplasm separated by a thin fibrous septa are sometimes evident.
Microcystic pattern consists of prominent cellular vacuolization and intercellular cystic change, which exhibit a characteristic lattice-like  or fenestrated  appearance.
The microcystic component recapitulates the terminal (intercalated) duct acinar unit contrasting the acinar differentiation of the solid variant  . Ductal cells are cuboidal with amphophilic or eosinophilic cytoplasm with distinct borders . These microcysts and vacuolated cells contain muci-carmine positive material, which may be abundant , .
Follicular pattern shows exaggerated acinar microcystic pattern in which dilated acini are lined by flattened epithelium and contain watery or colloid like material  . Focal areas of clear cells may be seen which may probably be due to degeneration ,, .
Papillocystic pattern has papillary projections within cystic spaces. The genesis of papillocystic happens in two ways retrogressive and neoplastic  . Retrogressive is a unilocular cyst with attenuated and swollen neoplastic cells accompanied by papillary excrescences. Apart from these morphologic growth patterns ACCs have also been observed to contain individual cell characteristics like. acinar cells, intercalated duct like cells. vacuolated cells, clear cells and nonspecific glandular cells  . All these cell types were seen in different fields in our case except the nonspecific glandular cells.
Other histologic variants like dedifferentiated , oncocytic . hybrid tumours , and well differentiated with lymphoid stroma have also been reported by various authors.
De-differentiated ACC presents itself with areas of low grade ACC and areas of de-differentiated high grade .ACC, or undifferentiated carcinoma within the same tumour  . Vascular and lymphatic invasion and regional lymph node metastasis arc common in de-differentiated tumours. An unusual hybrid tumour combining ACC include terminal duct carcinoma with acinous cell differentiation  , ACC ex-mixed tumor  , ACC with salivary duct carcinoma and ACC combined with muco-epidermoid carcinoma.
Well differentiated ACCs with lymphoid stroma present as well circumscribed encapsulated tumors with a solid or microcystic pattern in which tumor cells are surrounded and intermingled with prominent lymphoid response  .
This variable histologic appearance coupled with its uncommon occurrence accounts for diagnostic difficulty engendered by this tumor  . ACCs usually grow as solid sheets of serous cells frequently arranged in organoid pattern separated by a thin fibrous septa. Prominent lymphoid infiltrates are present in upto 1/3 rd of ACCs  . Psanunoma body-like calcifications may be present  which were not seen in our case.
In the case that we encountered, there were intercalated duct-like cells with basophilic material within the lumen. One area consisted of cystic degeneration with papillary projections into it. Differential diagnosis which we could consider were normal salivary gland since many areas showed normal acinar structures, sialadenitis or sialadenosis, mucoepidermoid carcinoma (Especially in areas showing micro-cystic pattern which could be differentiated by mucicarrnine staining)  .
Follicular thyroid carcinoma typically resembles ACC, which can be differentiated by thyroglobulin stainin  . Metastatic clear cell carcinoma and clear cell oncocytoma can be considered in the differential diagnosis as well but not in our case since the lesional site did not predominantly possess sheets of clear cells.
It was thought earlier that ACCs originate from serous acini but Eversole , Batsakis and Regezi have proposed that ACCs develop from stem or reserve epithelial cells located at tubuloacinar terminal of salivary gland duct Unit  , that is the intercalated duct region. Hayasi et al too thought that intercalated duct cell lines could be induced to transform into acinar type cells that produce ACC  .
Immunohistochemical analysis of this honor has been reported where in the acinar cells stain positive for amylase  , lactoferrin  and vasoactive intestinal polypeptide and negative for keratin , . Ductal luminal lining of cystic and follicular foci stains positive for keratin. epithelial membrane antigen (EMA) and carcinoembiyonic antigen (CEA)  .
Ultrastructural findings confirm the presence of zymogen-like granules and light mucous like granules in ACCs. Multidirectional differentiation toward acinar ductal and myoepithclial round bodies of low electron density have also been studied ,, .
| Summary|| |
A 60-year-old patient reported with a complaint of swelling, with duration of 10 years on the left side of the face. Initially it started as a small nodule and began to increase in size since four years .The swelling was firm and nodular. A provisional diagnosis of pleomorphic adenoma and carcinoma ex pleomorphic adenoma were given.
Histopathological examination revealed well-differentiated acinar cells with some normal salivary gland structures and diverse morphologic patterns, with all varieties of individual cell characteristics.
We are reporting this case for its diverse histological patterns and for its rarity as well.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]