On gross examination, the lesion was 6,5x5x4 cm in size, appearing as a white, solid mass with a whirling pattern on the cut surface, filling the right maxillary sinus completely, infiltrating into the orbital muscles and adipose tissue as well as orbital bone and soft tissue. No definitive capsule was identified. Histological examination showed tumor cells arranged in various amounts of solid, ductal, tubular and trabecular patterns. The tumor cells were mostly isomorphic in appearance, with round to oval or fusiform nuclei and bland nuclear chromatin and had a moderate amount of eosinophilic to clear cytoplasm. The cells were small and lacking nuclear atypia. Mitotic figures were rare and necrosis absent. Crystalloids resembling the tyrosinerich crystals were noted in focal areas. The surrounding muscle, fat and bone tissues were infiltrated by tumor cells. Perineural invasion was also noted. Immunohistochemical studies showed Cytokeratin 7 (CK), S100, SMA, p63, EMA positivity. CK20, GFAP, CK5/6, vimentin, CEA, CD10 were negative. The diagnosis was PLGA with detailed morphological and immunohistochemical evaluation (Figures 2–6). Reconstructive surgery was also performed. The patient did well and was free of disease at the last followup, twenty months after the last surgical intervention.
Figure 2: Various combinations of solid, tubular and trabecular patterns of the tumor (H&E, x10).
Figure 3: Small tubular structures showing central lumens (H&E, x20).
Figure 4: Ductal structures demonstrating central eosinophilic material (H&E, x20).
Figure 5: Bone invasion by the tumor (H&E, x10).
Figure 6: Smooth muscle actin positivity in the myoepithelial layer of the tumor nests (x20).
Typically, the palate is most commonly involved by PLGA. The buccal mucosa, retromolar region, upper lip and the base of the tongue are frequent locations[3,4,18]. Major salivary and lacrimal glands, nasopharynx, nasal cavity and paranasal sinuses are unexpected venues for PLGA[5-17].
There are only three reports mentioning a maxillary location of PLGA in the literature. One of them was intraosseous[19], the other simulated a maxillary odontogenic cyst around an impacted tooth[20]. The case from Charous et al. is the single report to our knowledge that resembles the current case arising from the maxillary sinus[6].
PLGAs are dominantly seen in females. The age varies between 16–94 years with a mean of 59 years[3,4]. Although the present case was a 35-year-old male when the specimen was sent to our pathology laboratory, the first mass appeared in his maxillary sinus when he was fourteen, meaning he is the youngest PLGA case in the literature to our knowledge.
Painless swelling is the most common symptom. The existence of the lesion has been observed from weeks to 40 years[3]. Our case came with a painless swelling on the right side of the face 21 years ago, then presented three more times in the last three years with local recurrences.
PLGA occasionally shows a firm, well-circumscribed, nonencapsulated mass with an average size of 2.2 cm[3] while the current case was 6.5 cm in greatest dimension as a recurrent lesion.
PLGA cases appear in a variety of configurations in trabecular, tubular, solid, papillary and cribriform patterns, which is a significant feature for these carcinomas[1]. The current case also showed a tubular appearance.
The neoplastic cells of the PLGAs show immunoreactivity with antibodies to cytokeratin, vimentin, S–100 protein, CEA, GFAP, EMA[3,21,22]. In our case, CK7, S100, SMA, p63, EMA positivity and CK20, GFAP, CK5/6, vimentin, CEA, CD10 negativity were observed.
Pleomorphic adenoma (PA) and adenoid cystic carcinoma (AdCC) are included in the differential diagnosis. Distinguishing PLGA from PA is often not possible on a cytomorphologic basis. PA is composed of proliferating epithelial, stromal and myoepithelial cells which lack an infiltrative pattern that is characteristic for PLGA[1]. Although PA of the minor glands are often unencapsulated, they do not infiltrate the adjacent tissues such as fat, muscle or bone. Myxochondroid and chondroid areas are present more commonly in PA than PLGA[1].
Distinguishing PLGA from AdCC is mostly based on cytologic properties. Cells in PLGA are more round to oval with bland nuclear chromatin and a moderate amount of eosinophilic to clear cytoplasm, in contrast to AdCC that has more basaloid features. Furthermore, large pseudocystic spaces are more characteristic for AdCC than PLGA. The solid areas of PLGA also lack the nuclear pleomorphism, small and angular nuclei, necrosis and mitotic activity that are often seen in the solid variant of AdCC[3,22,23]. The current case was an infiltrative lesion with no significant or atypical mitosis and necrosis.
Treatment includes complete surgical excision. Maxillectomy and right orbital exenteration were performed in our case. Radiotherapy (RT) was performed after both the first and the second operations and chemotherapy was carried out after the last operation together with RT.
PLGA has a relatively good prognosis[3,4,24]. Our patient did well postoperatively and he was free of disease at the last follow-up despite the three recurrences in a 21-year period.
In conclusion, the maxillary sinus is a very rare location for PLGA. As its name implies, this is a low-grade malignancy and the progression and the treatment can take a long time, sometimes causing vital tissue loss as in the current case. PLGA should be kept in mind in the differential diagnosis, even in rare sites in the head and neck.
ACKNOWLEDGEMENT
We would like to respectfully offer our regards to Prof. Dr.
Feriha Öz for her experience and knowledge on the basis of
the initial pathology report in 1988.
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