NATIONAL JOURNAL OF MEDICAL RESEARCH print ISSN: 2249 4995│eISSN: 2277 8810 Volume 4│Issue 4│Oct – Dec 2014 Page 380 CASE REPORT DIFFERENTIATED MALIGNANT MYOEPITHELIOMA OF THE PAROTID GLAND: A RARE CASE REPORT Jagannath Dev Sharma 1 , Kuddush Ahmed 2 , Tashnin Rahman 3 , Mridul Sarma 4 , Amal Chandra Kataki 5 Authors Affiliation: 1 Professor and Head of Pathology, Dr.B Borooah Cancer Institute, Guwahati; 2 Head and Neck Oncology, Dr. B Borooah Cancer Institute, Guwahati; 3 Head and Neck Oncology. Dr.B Borooah Cancer In- stitute, Guwahati; 4 Surgical Oncology, Guwahati Medical College and Hospital, Guwahati; 5 Gynecologic Oncology, Dr. B Borooah Cancer Institute, Guwahati Correspondence: Dr. Jagannath Dev Sharma, Email: dr_j_sarma@rediffmail.com ABSTRACT Malignant myoepithelioma (MM) is an epithelial malignant tumor in which predominant differentiation of the tumor cells are myoepithelial in nature. Dedifferentiated MM is an extremely rare entity. We report here a rare case of the parotid tumor of dedifferentiated MM with its many morphological and immuno- histochemistry features. Keywords: Dedifferentiated, malignant myoepithelioma, parotid gland, tumor INTRODUCTION Malignant myoepithelioma (MM) is an epithelial malignant tumor in which predominant differentia- tion of the tumor cells are myoepithelial in nature and it was considered to be an extremely rare enti- ty. [1] However, it may be more common than pre- viously thought. [2] We report here a rare case of the parotid tumor showing pleomorphic giant cell rich myoepithelioma, which was also been previously described as a dedifferentiated MM. [3] CASE REPORT A 27 - year -old male presented at the head and neck oncology OPD of a regional cancer center with a swelling on the right cheek region. The swelling was present since one year with a recent history of rapid increase in its size from the last one month. There was no associated facial defor- mity present. On examination; there was a firm to hard, non-tender, and mobile swelling of the right parotid gland. The swelling was 5cmX 4cm in its maximum dimension. The skin overlying the swel- ling was free. The clinical diagnosis of a parotid tumor was provisionally made. Fine needle aspiration cytomorphology (FNAC) of the swelling was done. FNAC revealed pleomor- phic round to epitheloid, plump spindly cells dis- crete and in loose clusters with moderate amount of granular cytoplasm and nucleolar prominence and many mitotic figures. No ductal and acinar cell groups were seen and also seen were many osteoc- lasts like giant cells and myxoid material in the background [Figure 1a]. The patient underwent wide excision (adequate pa- rotidectomy) of the right parotid tumor. Grossly the post-operative specimen measured 4.5cm X 3.5 cm. The tumor was solid, homogeneous grey white in color, with areas of necrosis and myxoid change, but the adjoining salivary tissue was unremarkable [Figure 1b]. Histopathological examination (HPE) showed predominantly a pleomorphic spindle cell tumor with necrosis, hemorrhage, atypical mitotic figures and many osteoclast like tumor giant cells. Inter- mingling with it were scattered foci of epithelial cell clusters having clear cytoplasm in many and an occasional attempt at acinar formation [Figure 1c]. Immunohistochemistry (IHC) was done. IHC staining showed positivity for the expression of vimentin [Figure 2a], focally positive for cytokera- tin (CK) [Figure 2b], and S-100 [Figure 2c]. The diagnosis of MM with dedifferentiated morpholo- gy was established after HPE and IHC.