Myoepithelial carcinoma arising in recurrent pleomorphic adenoma in maxillary sinus
A 39-year-old lady presented with painless progressive swelling on the right cheek and right side of palate for 2 months. On examination there was a 2 × 2 cm firm, non-tender swelling. She had undergone a surgery elsewhere 2 years back for a palatal swelling, the details of which were not available. Computed tomography (CT) revealed a 29 × 28 mm enhancing mass in the right side of hard palate with large defect in the palatine process, extending into right maxillary sinus and nasal cavity, anteriorly up to the vestibule and inferiorly into the oral cavity. Right inferior partial maxillectomy was done with excision of the tumor which was sent for histopathological examination. Intraoperatively there was an encapsulated 6 × 4 × 3 cm size mucosa covered mass filling right maxillary sinus.\nTwo years later, she presented with recurrent swelling in right infraorbital region for 4 months associated with mild pain. On examination, the swelling was small, firm and non-tender. CT revealed a tumor over anterior wall of right maxillary sinus extending to soft tissues anterior to right maxilla. The tumor was excised via Caldwell-Luc approach and sent for histopathological evaluation.\nSubsequently, 1 year later, she presented with rapidly progressive swelling of bilateral cheeks and lateral surface of nose for a month, associated with breathing difficulty. On examination there was a 6 × 5 cm red tender swelling on the face with flattening contour of nose infraorbitally, extending to upper lip with obliteration of bilateral nasal cavities. On CT, there was an extensive heterogeneously enhancing soft tissue density lesion in both maxillary sinuses with destruction of the walls and extension into both ethmoid sinuses, nasal cavity, maxillary alveoli, soft tissue of upper lip, bilateral infratemporal region and both orbits. There was no intracranial extension. The mass was excised surgically. Intraoperatively, there was extensive friable tumor adherent to the skin, involving bilateral maxillary cavities with extension into the right orbit, right nasal cavity with erosion of septum and floor of mouth, both pterygopalatine fossa and bilateral pterygoid muscles. The tumor was sent for histopathological examination.\nThe initial excision specimen was partial right maxillectomy, with a tumor at the superior aspect. The tumor measured 4.5 × 3 × 2.5 cm on gross examination, with a grey white firm cut surface. Microscopy [] showed pleomorphic adenoma composed of sheets of myoepithelial cells and ductular structures lined by epithelial cells set in chondromyxoid stroma with extensive hyalinization, foci of myxoid change and osseous metaplasia. There was no evidence of malignancy.\nThe excised recurrent tumor grossly consisted of multiple soft tissue fragments, 0.5-1.8 cm in maximum dimension. Microscopy showed pleomorphic adenoma, without atypia or any evidence of malignancy.\nThe third specimen was initially sent to pathology intraoperatively for frozen section, wherein a provisional diagnosis of cellular neoplasm with atypical features suggestive of malignancy was given. Subsequently, the entire specimen was received for histopathological evaluation.\nTumor specimens from right and left maxillary sinuses were received separately. The specimen from right maxillary sinus was an irregular soft tissue measuring 5 × 2.5 × 2 cm, with a partly solid and partly cystic cut surface. Excised tumor from left maxillary sinus was received as multiple irregular fragments of soft tissue, largest measuring 6 × 5.5 × 2.5 cm, with greyish yellow cut surface containing hemorrhagic areas.\nMicroscopy [Figure –] showed a cellular tumor composed of lobules, nests, trabeculae and cords of polygonal cells with eccentrically placed hyperchromatic nuclei, mild to moderate pleomorphism, inconspicuous nuceoli, mitotic activity (up to 3/10 high power field (HPF)) and moderate amounts of clear cytoplasm, surrounded by fibromyxoid stoma with hyalinization. There were large areas of geographic necrosis, foci of cystic change and hemorrhage. Lymphovascular invasion was present. There was infiltration of the adjacent bone. Immunohistochemically, the neoplastic cells were positive for S100 [], pancytokeratin [] and focally [] for smooth muscle actin (SMA). A diagnosis of myoepithelial carcinoma arising in a recurrent pleomorphic adenoma was given.