|Year : 2013 | Volume
| Issue : 2 | Page : 142-146
FNAC diagnosis of adenoid cystic carcinoma of the maxillary sinus: A case report with emphasis on cytological differential diagnosis
Jagadish Hosmani, Ramakant Nayak, Mayuri Kulkarni, Vijayalakshmi S Kotrashetti, Pradeep Somannavar
Department of Oral Pathology and Microbiology, Maratha Mandalís Nathajirao G. Halgekar Institute of Dental Sciences, India
|Date of Web Publication||21-May-2013|
Vijayalakshmi S Kotrashetti
Department of Oral Pathology and Microbiology, Maratha Mandalís Nathajirao G. Halgekar Institute of Dental Sciences and Research Centre, Belgaum Ė 590 010, Karnataka
Source of Support: None, Conflict of Interest: None
Fine needle aspiration cytology (FNAC) has been employed with increasing frequency as a diagnostic tool for lesions of the major and minor salivary glands. The reported sensitivity and specificity of FNAC of salivary gland lesion ranges approximately between 60 and 100% and 90 and 100%, respectively. The major reason for varied statistics in diagnosis is due to its diverse morphological patterns and overlapping features that makes it a challenging job for pathologists to give a precise diagnosis. If established diagnostic criteria are present and strictly followed, a great majority of common variations of non-neoplastic lesions, benign and malignant salivary gland tumors can be diagnosed with high level of accuracy with FNAC. A patient with high operation risk may benefit from the information obtained by FNAC. We report a case of adenoid cystic carcinoma of maxillary sinus in a 46-year-old male patient diagnosed mainly through FNAC and also discuss the possible differential diagnosis and pitfalls of FNAC in diagnosing adenoid cystic carcinoma.
Keywords: Adenoid cystic carcinoma, cytology, FNAC pitfalls, maxillary sinus, salivary glands
|How to cite this article:|
Hosmani J, Nayak R, Kulkarni M, Kotrashetti VS, Somannavar P. FNAC diagnosis of adenoid cystic carcinoma of the maxillary sinus: A case report with emphasis on cytological differential diagnosis. J NTR Univ Health Sci 2013;2:142-6
|How to cite this URL:|
Hosmani J, Nayak R, Kulkarni M, Kotrashetti VS, Somannavar P. FNAC diagnosis of adenoid cystic carcinoma of the maxillary sinus: A case report with emphasis on cytological differential diagnosis. J NTR Univ Health Sci [serial online] 2013 [cited 2020 May 27];2:142-6. Available from: http://www.jdrntruhs.org/text.asp?2013/2/2/142/112355
| Introduction|| |
The salivary gland histopathology is extremely varied and complex that requires differentiation between neoplastic and non-neoplastic lesion, benign from malignant tumors of salivary gland. This differentiation is extremely important because majority of the salivary gland tumors are treated surgically. Thus, identifying malignant tumor either preoperatively or intraoperatively is crucial. Clinical history and examination is equally important. There may be classic signs and symptoms that may suggest malignancy, but at times majority of malignant salivary gland tumors have unremarkable features and are not readily distinguishable from their benign counterparts on clinical criteria alone. Preoperative imaging such as computed tomography (CT) and magnetic resonance imaging (MRI) provide certain features suggestive of malignancy, but imaging alone is not reliable for making diagnosis. 
Fine needle aspiration cytology (FNAC) of suspected salivary gland lesions has been widely used as a diagnostic procedure, which aids in preoperative diagnosis and management of patients. It has acquired an edge over incisional biopsy and frozen section.  The reported sensitivity and specificity of FNAC is high for benign salivary gland neoplasm, but is less predictable for malignant tumors. When FNAC smear reveals classic features of one or the other tumor, it becomes satisfying for a cytopathologist to designate benign or malignant nature of neoplasm and further subtype it. However, diverse morphological patterns and overlapping features of the salivary gland tumor make it a challenging job for a pathologist to give precise diagnosis at times. ,,
Thus, the aim of the present article is to report a case of adenoid cystic carcinoma (ACC) arising from maxillary sinus and discuss the pitfalls and differential diagnosis in diagnosing ACC through FNAC.
| Case Report|| |
A 46-year-old male patient reported to the institute complaining of swelling in the left cheek region since 4 months and also difficulty in breathing. Initially, swelling was noticed on the left palatal region of the maxilla, which gradually increased to the present size. Swelling was associated with pain, which was continuous in nature and the patient felt difficulty in breathing through nose. The patient was taking ayurvedic medication for swelling, which did not help in the reduction of swelling or pain, but subsequently noticed extraoral swelling in the left cheek region.
On extraoral examination, swelling was firm, measuring about 4 × 5 cms in dimension with fairly well-defined boarders, the swelling extending to infraorbital margin superiorly, inferiorly 1 cm below ala tragus line, medially obliterating the nasolabial fold. Overlying skin was stretched and left eye appeared to be obliterated with epiphora [Figure 1]a.
|Figure 1: (a) Photograph showing extraoral swelling and obliteration of the left side of the eye, (b) Photograph showing intraoral swelling on the left palatal region, (c) Photograph showing orthopantomograph, which is nonspecific, (d) CT scan showing infi ltrating mass in maxillary sinus, lateral nasal wall, and ethmoid air sinus|
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On intraoral examination, swelling was noticed extending palatally from 21 to 28 without crossing the midline measuring approximately 5 × 2 cms. It was firm and tender on palpation and showed obliteration of left vestibule [Figure 1]b.
Orthopantomogram (OPG) findings were nonsignificant [Figure 1]c. CT scan demonstrated enhanced infiltration of mass to the adjacent area extending to anterior wall of maxillary sinus, lateral nasal wall, and ethmoid air sinus. Erosion of palate on the left side was observed [Figure 1]d.
Based on these findings the clinical differential diagnosis of aggressive odontogenic tumor, malignant salivary gland tumor, and tumor of maxillary sinus was given.
FNAC of the lesion was performed. The Papanicolaou's (PAP) stained smear showed monomorphic population of basaloid cells in clumps, clusters, and as single cells. The tumor cells appeared round to oval showing hyperchromatic nuclei that appeared uniform in size with scanty cytoplasm [Figure 2]a. The cells showed minimal pleomorphism. Eosinophilic pale semitranslucent globules were seen dispersed throughout the smear. Most areas showed tumor cells surrounding these hyaline globules [Figure 2]b. Based on these features and CT scan report diagnosis of ACC was made.
|Figure 2: (a) Photomicrograph showing hyperchromatic basaloid cells with hyaline globules (10×, PAP), (b) Photomicrograph showing hyperchromatic cells with scanty cytoplasm in mucinous back ground (40×, PAP), (c) Photomicrograph showing cribiform pattern with darkly stained cell (4×, H & E), (d) Photomicrograph showing cribiform pattern with eosinophilic material (10×, H & E)|
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Incisional biopsy was done for further confirmation, hematoxylin and eosin (H&E) stained sections showed deeply stained uniform cells resembling basal cells arranged in a duct-like pattern. The central portion of the duct showed presence of mucoid material giving a typical cribriform/Swiss cheese appearance [Figure 2]c and 2d. The stroma surrounding the tumor island was hyalinized. These features confirmed the diagnosis of ACC.
Treatment planned for this patient was radical resection of the lesion. On explanation regarding the treatment plan and its prognosis, patient refused to take further treatment. He wanted only symptomatic relief and subsequently was lost for follow-up.
| Discussion|| |
ACC, earlier known as cylindroma, is a tumor arising from mucous glands. It was first described by Theodor Billroth (1856). He studied its histologic features and described the long amorphous compartments as "cylinders".  The currently accepted terminology ACC was proposed by Foote and Frazell (1953). The tumor is slow growing and occurs more commonly in major salivary gland, mainly parotid.  About 50-60% of ACC occur in minor salivary gland, which present typically as swelling or mass. Palate is the most common site of occurrence. Pain is a variable finding. ,, Besides its occurrence in salivary glands it is reported to occur in other sites such as the ceruminal glands of ears, the breast, and the vulva.  Rarely presents as primary intraosseous tumors of mandible and maxilla. 
The mode of spread of this tumor is characteristic. It has a tendency for perineural spread accounting for pain in about 50% of cases. The propensity of this tumor to invade bone and spread along the base of the skull results in extensive intracranial invasion and involvement of the cranial nerves. Lymphatic spread is very rare and in case of long-standing cases distant metastasis occurs via blood stream to lungs and bones. 
Cytologically, the smear patterns of ACC are characterized by a mixture of small, uniform, basaloid cells with high nuclear to cytoplasmic ratios and metachromatic stroma. The cytologic features frequently mimic the histologic patterns showing cribiform or tubular patterns while exclusively solid sheets of tumor cells are seen in the solid variant or anaplastic ACC. The chromatin appears coarse but uniform without identifiable nucleoli, and nuclear pleomorphism is minimal. The background of ACC is usually populated by scattered naked nuclei of tumor cells. ,,
Although the stroma of ACC is characteristic, it can be seen in several other salivary gland tumors. The interface between tumor cells and stroma often is sharply demarcated. The diagnosis of the well-differentiated or type of ACC is relatively straightforward. The microcystic spaces containing the hyaline globules and cylinders of metachromatic stroma are easily identified in such cases. However, metachromatic stroma is not specific for or unique to ACC; it is also found in cases of polymorphous low-grade adenocarcinoma, basal cell adenoma, pleomorphic adenoma, epithelial-myoepithelial carcinoma, and basal cell carcinoma. Thus, cases of ACC lacking architecture may be impossible to distinguish from other basaloid tumors. ,
In the present case, the smear revealed typical hyaline globules with monotonous hyperchromatic basaloid type of cells that were mostly suggestive of pattern of ACC or tubular variant of basal cell adenoma. But CT scan in the present case demonstrated erosion of bone suggestive of aggressive behavior of the lesion, which made us to rule out basal cell adenoma. FNAC of tubular variant of basal cell adenoma shows presence of numerous cell clusters with regular round or oval nuclei and sparse cytoplasm. Prominent hyaline globules are seen that makes it difficult to differentiate between and tubular variant of ACC. However, identification of hyaline stroma is always critical for the diagnosis of ACC, as most cases show its presence except for solid variant. ,, Other tumors that show cytologic features similar to ACC with their differentiating features are explained in [Table 1].
|Table 1: Differential Diagnosis and Diagnostic Criteria for Acc and Look-Alike Tumors[7,8]|
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This suggests that genuine problems do occur in typing of salivary gland neoplasms based on cytology and it needs to be emphasized. Even though diagnostic problems in FNAC of salivary glands have been discussed by various authors extensively, the major drawback includes the sampling of the lesion and the site from where the sample is obtained. , In case of pleomorphic adenoma, a portion of the aspirated material may show features very similar to those obtained from ACC. In contrast, the sample of ACC may demonstrate a rectangular pseudotrabecular myxoid stroma. In such cases, the cellular distinction may be very difficult; with the possibility of overdiagnosis and underdiagnosis. Thus, cytological diagnosis of salivary gland should be approached in a stepwise manner. In the first step, decide whether the lesion is salivary origin or a clinical mimic. In the next step, identify cells and their morphology to classify them as cystic, inflammatory, and neoplastic process. This is possible only with vast experience and strictly following the established diagnostic criteria, which will provide a high level of accuracy in distinguishing between various subtypes. ,,
Despite this, there always remains a proportion of problematic cases of 10-15%, depending on the level of experience for which cytological criteria have not yet been established.  In such cases the uncertainty of the lesion should be conveyed to the surgeon. Some authors have even suggested that the relative rarity of salivary gland tumor makes it difficult to obtain FNAC. Thus, accurate interpretation may be difficult even for the most experienced cytologist. , For the present case, incisional biopsy was performed that further confirmed the diagnosis of ACC.
| Conclusion|| |
Our case had a typical clinical presentation of a palatal swelling with erosion of the floor of the maxillary sinus in CT scan. On FNAC, the smear revealed the presence of monomorphic hyperchromatic basaloid cells in clumps with minimal pleomorphism, eosinophilic pale semitranslucent globules dispersed throughout the smear suggestive of ACC. Taking into consideration the limitations of FNAC, the final diagnosis of ACC was confirmed through the incisional biopsy that revealed the characteristic pattern. Hence, it is necessary to follow certain strict guidelines for diagnosis of salivary gland pathology. It is also prudent on occasions to limit the FNAC report to differential diagnosis. Finally, communication and cooperation between a clinician and a cytopathologist can solve the riddle.
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[Figure 1], [Figure 2]