|Year : 2018 | Volume
| Issue : 4 | Page : 90-92
Papillary cystic variant of acinic cell carcinoma of parotid with preoperative diagnostic difficulty on fine-needle aspiration cytology: A case report
Sovan Sarang Dhar1, Subhalaxmi Rautray2, Saroj Kumar Das Majumdar1, Asaranti Kar3, Dillip Kumar Parida1
1 Department of Radiotherapy, All India Institute of Medical Sciences, Bhubaneswar, Odisha, India
2 Department of Otorhinolaryngology, Srirama Chandra Bhanja Medical College, Cuttack, Odisha, India
3 Department of Pathology, Srirama Chandra Bhanja Medical College, Cuttack, Odisha, India
|Date of Web Publication||26-Dec-2018|
Dr. Saroj Kumar Das Majumdar
Department of Radiotherapy, All India Institute of Medical Sciences, Bhubaneswar, Odisha
Source of Support: None, Conflict of Interest: None
Acinic cell carcinoma (ACC) is an unusual salivary gland neoplasm with unpredictable behavior. Papillary cystic variant of ACC (PCV-ACC) is even rarer and commonly occurs in the parotid. It has high local recurrence rate and poorer prognosis compared to classic type of ACC. Majority of cases occur in younger age group and exhibit diagnostic difficulty on cytology. Its diagnosis is based on histopathological examination. We report a case of PCV-ACC of the right parotid gland in a 15-year-old female which was misdiagnosed as a benign lesion on cytology emphasizing the importance of histopathological examination in parotid masses. Superficial parotidectomy followed by total parotidectomy was performed in the present case, and the case is under regular follow-up basis for the last 8 months without any disease.
Keywords: Acinic cell carcinoma, cytology, histopathology, papillary cystic variant, parotid
|How to cite this article:|
Dhar SS, Rautray S, Majumdar SK, Kar A, Parida DK. Papillary cystic variant of acinic cell carcinoma of parotid with preoperative diagnostic difficulty on fine-needle aspiration cytology: A case report. Oncol J India 2018;2:90-2
|How to cite this URL:|
Dhar SS, Rautray S, Majumdar SK, Kar A, Parida DK. Papillary cystic variant of acinic cell carcinoma of parotid with preoperative diagnostic difficulty on fine-needle aspiration cytology: A case report. Oncol J India [serial online] 2018 [cited 2019 Jun 26];2:90-2. Available from: http://www.ojionline.org/text.asp?2018/2/4/90/248531
| Introduction|| |
Acinic cell carcinoma (ACC) is an unusual malignancy of the salivary glands and accounts for 2.5%–4% of all the parotid gland tumors. Papillary cystic variant of ACC (PCV-ACC) is a rare entity and is mostly confined to both the major and minor salivary glands. The most common age group of presentation for PCV-ACC is 16–40 years. ACC is a low-grade malignancy, whereas PCV-ACC is a high-grade one with poor prognosis requiring a prompt and accurate preoperative diagnosis. Here, we report a case of PCV-ACC of the right-sided parotid gland in a 15-year-old female.
| Case Report|| |
A 15-year-old female patient presented with painless lump over right side of the face just below the lower ear lobule for 10 months. Physical examination showed a nontender mass of size 2.5 cm × 2.5 cm with hard in consistency over the right side face just inferior to ear lobule. Ultrasonography of the neck and parotid showed a well-defined solid cystic mass of size 1.7 cm × 1.6 cm at the right parotid gland. Fine-needle aspiration cytology (FNAC) from the swelling revealed the presence of salivary acinar cells with scattered lymphocytes, histiocytes, and occasional foreign body giant cells suggesting diagnosis of chronic nonspecific sialedenitis [Figure 1]a and [Figure 1]b. Due to solid cystic mass on ultrasonography, the patient was planned for surgical removal of the tumor for histopathological confirmation of the diagnosis. Superficial parotidectomy was performed. Gross specimen measured about 3.5 cm × 4.5 cm × 3 cm and cut surface revealed a large well-circumscribed cystic lesion of size 2.6 cm × 2.2 cm filled with dark-brown jelly-like material. All the surgical margins were negative. Histopathological examination revealed the presence of normal salivary gland tissue with fibrocollageneous capsule and scanty tumor tissue attached to capsule. Tumor tissue was arranged in the papillae with fibrovascular core and small nests [Figure 2]a. Papillae were lined by hobnail cells, cuboidal cells, and vacuolated cells [Figure 2]b. There were deposition of proteinaceous substances and inflammatory cell infiltration. Papillary folds were interspersed with cystic spaces [Figure 2]c. There was no atypical mitosis or necrosis observed. All the histopathological findings confirm the diagnosis of PCV-ACC. Total parotidectomy was performed without any residual on pathological examination. At present, the patient is under regular follow-up for the last 8 months without any disease.
|Figure 1: Cytology smear (Diff-Quik stain) showing (a) salivary acinar cells with inflammatory cells (×40) and (b) salivary acinar cells with few lymphocytes (×100)|
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|Figure 2: Photomicrograph (H and E, ×400) showing (a) tumor tissue arranged in papilla with presence of cystic spaces lined by neoplastic epithelial cells, (b) round to polygonal tumor cells with hyperchromatic nuclei and presence of nuclear hobnailing, and (c) tumor tissue with numerous dilated cystic spaces|
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| Discussion|| |
ACC is usually a low-grade epithelial cell malignancy with acinic serous differentiation that constitutes about 1%–6% of all salivary gland neoplasms., These tumors are destructive neoplasms with unpredictive behavior and have a female predilection. Parotid is the most common site for ACC constituting approximately 86% followed by others such as intraoral minor salivary glands, submandibular glands, and sublingual glands. Majority of cases are unilateral and up to 3% of tumors can be bilateral. ACC usually presents as a slow-growing and nontender swelling with a tumor size of <3 cm, and pain may occur spontaneously or on palpation. Previous radiation exposure and familial predisposition are the possible causes for ACC. According to few literature, it is a hormone-dependent tumor.,
ACC may arise from neoplastic transformation of the terminal duct cells, i.e., intercalated duct cells or normal serous acinar cells. ACCs have a variety of morphological and cytological appearances. Basing upon different histomorphological features, a verity of architectural patterns may be found in ACC: solid, solid-lobular, acinar-microcystic, papillary cystic, tubuloductal, follicular and macrocystic, and dedifferentiated. Solid and microcystic subtypes are major histomorphologic patterns for ACC, whereas papillary cystic variant is a rare variant with a diagnostic challenge on cytology. In papillary cystic variant, there is transition of usual dense cellularity into papillary folds interspersed with cystic spaces.
Most of the patients with PCV-ACC have been reported in younger age group, i.e., 16–40 years as compared to the classic type where it is the fifth decade of life and there is a female predominance., The present case is a young female with PCV-ACC involving the right parotid gland supporting the literature.
PCV-ACC is difficult to diagnosis basing upon FNAC. The features of classical ACC by cytology method is well known showing loosely clustered bland looking acinar cells resembling nonneoplastic salivary acinar cells. Well-differentiated ACC is distinguished from normal salivary gland acini by the presence of cell dissociation and some bare tumor cell nuclei.
The cytological diagnosis of PCV-ACC is difficult than classical type of ACC due to dilution of overall cellularity by cystic fluid, leading to a benign diagnosis, different architectural patterns such as prominent papillary architecture with more cohesive cells, morphological changes of tumor cells due to suspension in the cystic fluid, and presence of metaplastic oncocytic cells. The present case on FNAC shows the presence of acinar group of cells resembling normal salivary acinic cells, but there is absence of any cell dissociation or any bare tumor cell nuclei missing the clue toward the initial diagnosis of PCV-ACC even ACC.
Cystic nature of the cell of PCV-ACC may lead to a misdiagnosis of cystadenocarcinoma., Furthermore, cystic fluid dilutes the overall cellularity leading to a benign diagnosis. Therefore, during difficult cytological interpretation of such cases, cystic fluid may be subjected for cell block preparation to improve diagnosis.
Cytologically, the presence of malignant squamous, hybrid cells, and mucophages within the dirty mucinous and necrotic background in case of mucoepidermoid carcinoma and tumor cells with bland nucleus and abundant vacuolated cytoplasm along with intracytoplasmic lumina in a mucoid background and mucin positivity in case of papillary cystadenocarcinoma helps to rule out these two malignancies from PCV-ACC.,
The diagnosis of PCV-ACC is based on histopathological examination. Microscopically, the tumor is encapsulated with capsular invasion being a common finding and papillary folds are interspersed with cystic spaces. There may be presence of either small cysts with scanty papillary projections or presence of large cystic spaces with more papillary growths, stalks, fronds, or masses of glandular epithelium supported by thin fibrovascular cords.
There is a presence of fibrous connective tissue encapsulating the tumor with marginal infiltration. Different type of cells may exist inside the tumor such as acinic cells, vacuolated cells, intercalated cells, nonspecific glandular cells, and clear cells. Acinic cells are polyhedral cells containing abundant finely granular cytoplasm (amphibolic/pale eosinophilic/basophilic) with small regular hyperchromatic nuclei, a prominent nucleolous and presence of strongly periodic acid–Schiff (PAS) and D-PAS positive granules. Hobnailing or tombstoning pattern of the luminal cells is due to bulging of the apical portions of lumen lining cells into the lumen with release of secretions and is the characteristic feature of the PCV-ACC.
Instead of a low malignant behavior, ACC has a tendency for local recurrence (8.3%–45%), regional lymph node involvement (3.8%–16%), and distant metastasis (2.6%–14%) with a death rate of 1.3%–26%.
ACC is a low-grade malignancy with 5-year survival is approximately 90%. However, papillary cystic variant is high grade with poor prognosis in comparison to other variants of ACC and is universally fatal within 10 years.,, Complete surgical resection is the standard treatment of primary salivary neoplasm. Total parotidectomy is the mainstay of treatment for PCV-ACC. Few literature says complete surgical resection of tumor with prophylactic neck dissection is required for such a high-grade variant.
In summary, because of clinical, radiologic, and cytologic overlap features, parotid masses should be undergone histopathological examination for confirmation of the diagnosis. PCV-ACC is a rare entity with diagnostic difficulty on cytology. The specific treatment different to classical ACC and prognosis of patient is unknown and needs further evaluation.
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The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
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