Journal of Cytology

CASE REPORT
Year
: 2008  |  Volume : 25  |  Issue : 3  |  Page : 115--116

Fine needle aspiration cytology of low-grade mucoepidermoid carcinoma of the parotid gland: A diagnostic challenge


Asha B Rupani, Vikas S Kavishwar, Vynkatesh Achinmane, Gururaj V Puranik 
 Department of Pathology, T N Medical College and B Y L Nair Ch Hospital, Mumbai Central, Mumbai - 400 008, India

Correspondence Address:
Asha B Rupani
5, Sapna Hsg Society, Sector-4, Vashi, Navi Mumbai - 400 703
India

Abstract

Of the salivary gland tumors, mucoepidermoid carcinoma is probably the most difficult to diagnose accurately by aspiration cytology. It is the second most common tumor in the pediatric age group in parotid gland after pleomorphic adenoma and differentiating between both can be diagnostically challenging. We are hereby presenting a case of 13 year old female child with right parotid lesion. The combination of overlapping intermediate and mucus producing cells with abundant background and intracytoplasmic mucin helped us in making the diagnosis of intermediate mucoepidermoid carcinoma. Subsequently total parotidectomy revealed a low grade mucoepidermoid carcinoma. Hence we concluded that abundant mucin with good cellularity can be seen in low grade mucoepidermoid carcinoma. Grading of mucoepidermoid carcinoma is also important to determine the prognosis.



How to cite this article:
Rupani AB, Kavishwar VS, Achinmane V, Puranik GV. Fine needle aspiration cytology of low-grade mucoepidermoid carcinoma of the parotid gland: A diagnostic challenge.J Cytol 2008;25:115-116


How to cite this URL:
Rupani AB, Kavishwar VS, Achinmane V, Puranik GV. Fine needle aspiration cytology of low-grade mucoepidermoid carcinoma of the parotid gland: A diagnostic challenge. J Cytol [serial online] 2008 [cited 2021 Apr 23 ];25:115-116
Available from: https://www.jcytol.org/text.asp?2008/25/3/115/44051


Full Text

 Introduction



Mucoepidermoid carcinoma is a tumor commonly seen in parotid gland in pediatric age group. However there are very few studies, describing the cytological features of this entity and it is important to diagnose it on cytology as the subsequent treatment depends on it. [1],[2] We are hereby reporting a case where we faced diagnostic difficulty on cytology.

 Case Report



A 13 year-old female child came with complaints of swelling in her right preauricular region that had gradually increased in size over three months. There was mild associated pain and tenderness. On examination, the swelling was found to be well-defined, firm, tender, and measured 4 x 2.5 centimetres in the right parotid gland. The overlying skin was unremarkable and the aspirate was a stringy mucoid material. The slides were stained with Papanicolaou (PAP) and May-Grünwald-Geimsa (MGG) stains. Microscopy showed a cellular aspirate with a mucinous background [Figure 1]. The mucus was pale green and translucent on PAP staining and a dirty, dark pink after MGG staining. There were numerous cell clusters as well as single cells with two types of cells. One type of cell was larger in size and showed intracytoplasmic mucin with small nucleus. On MGG staining, these cells appeared to have vacuolated cytoplasm whereas they appeared to have pale cytoplasm after PAP staining. The other cell type resembled ductal epithelium with moderate to scant cytoplasm and a central nucleus (intermediate cells) and showed overlapping with mild anisonucleosis. The mucus-producing cells were arranged around the clusters of the intermediate cells [Figure 2]. No cells with squamoid features were noted. Considering the overall features, a diagnosis of intermediate mucoepidermoid carcinoma was made. The patient underwent a total parotidectomy along with removal of surrounding nodes. The tumor was 3 x 2.5 x 2 centimetres in size, well-circumscribed, whitish in colour and tiny cysts filled with mucinous material were noted on the cut surface. Histopathological examination showed classic features of a low-grade mucoepidermoid carcinoma with no nodal involvement. There were prominent lymphoid follicles in the tumor periphery. The postoperative course of the patient was uneventful and she has no complaints to date on follow-up.

 Discussion



Mucoepidermoid carcinoma is the second most common tumor of the parotid gland in the pediatric age group after pleomorphic adenoma. [3] Of all salivary gland tumors, mucoepidermoid carcinoma is probably the most difficult to accurately diagnose by aspiration cytology. Identification of three types of cells: intermediate, mucus-producing, and squamous cells in the smear is most predictive of mucoepidermoid carcinoma. [1] Another study has laid emphasis on the overlapping epithelial groups. [2] Using these features together, the sensitivity and specificity of accurately diagnosing mucoepidermoid carcinoma are 97 and 100%, respectively. [2] The stringy mucin aspirated in our case is also important as the stringy nature helps to differentiate it from mucin seen in pleomorphic adenoma. [2] Differentiation from pleomorphic adenoma can be diagnostically challenging in the presence of mucinous metaplasia. Also, the myxoid ground substance can sometimes be mistaken for epithelial mucin, particularly after PAP staining, and in such cases, pleomorphic adenoma is misdiagnosed as being malignant. [4] A few cases of pleomorphic adenoma can show squamous cells and vacuolated, foamy cells, as seen in our case. [5] The presence of chondromyxoid stroma can be a useful clue in such cases. Cells with squamous differentiation were not seen in our case as smears may not be helpful to identify all types of cells.

Generally, the diagnosis is most difficult in low-grade mucoepidermoid carcinomas where thick mucinous material is seen in the background with a paucicellular smear. [3],[4] In such cases, mucoepidermoid carcinomas are mistakenly reported as benign cystic lesions. Intermediate-grade tumors show cellular aspirates with predominant, nonmucinous intermediate cells and a few mucin-secreting cells, as also seen in our case. [3] Grading of mucoepidermoid carcinoma is also important to determine the prognosis. The combination of numerous, overlapping, intermediate and mucus-producing cells with abundant background and intracytoplasmic mucin tilted the diagnosis in favour of intermediate-grade mucoepidermoid carcinoma in our case after excluding the possibility of a cystic lesion of the parotid gland and pleomorphic adenoma. However, histopathological examination confirmed the final diagnosis of a low-grade mucoepidermoid carcinoma. To conclude, abundant mucin with good cellularity can be seen in low-grade mucoepidermoid carcinomas and an effort should be made in the presence of extracellular mucin to look for a combination of intermingling intermediate cells and mucus-producing cells to make this diagnosis.

References

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