Contributed by Claudia Maria Salgado, MD, PhD, Rita Alaggio, MD and Sarangarajan Ranganathan, MD
Nine year-old male who presented with a non-painful, firm, round, parotid lump for about one week. Neck CT with contrast showed a well circumscribed, 1.5 cm enhancing mass within the anterior portion of the superficial lobe of the left parotid gland (Figure 1, Neck CT with contrast showing 1.5cm mass within the parotid gland).
FNA showed cellular specimen composed by single and cohesive epithelioid cells forming papillary structures. Final diagnosis: Positive for neoplasm. Epithelioid neoplasm, favor salivary gland neoplasm. FISH negative for MAML2 translocation.
The tumor was completely resected, and frozen section showed a cellular monotonous tumor. Defer to permanents. Neck dissection for levels 2, 3 and 4 was performed.
Gross examination of the surgical resected specimen revealed a 1.5 x 1.4 x 1.3 cm well-circumscribed mass into the left parotid gland, which appeared to be thinly encapsulated (Figure 2). The tumor was tan-pink, soft and friable and was located <0.1 cm from the deep margin (closest margin).
Histologic sections showed a well-circumscribed tumor surrounded by fibrous tissue with inflammation and hemorrhage with cholesterol clefts. The tumor is composed mostly by sheets of cells, areas with duct-like luminal structures and rare papillae (Figure 3A, H&E 4X). Inside of the ducts and in microcystic areas, there was eosinophilic colloid-like material with a "bubbly" appearance (Figure 3B, H&E 10X). The tumor cells were medium-sized, monotonous, with eosinophilic and sometimes vacuolated cytoplasm without zymogen granules. The nuclei were oval to round with open chromatin and visible single nucleoli (Figure 3C, H&E 20X). There was mild increase in mitotic activity. Around the tumor, normal serous salivary glands and adipose tissue are seen. No vascular or perineural invasion are identified. The inked margins of resection are free of tumor.
IMMUNOHISTOCHEMISTRY AND MOLECULAR STUDIES
Immunohistochemistry (IHC) shows tumor cells positive for cytokeratin 7 and S100, and negative for cytokeratin 5/6 and for P63. Ki-67 shows proliferative index of 20-30%. The tumor cells have also nuclear positive stain for GATA3 and cytoplasmic expression of mammaglobin (Figure 4, Immunohistochemistry. A, S-100. B, Ki67. C, Mammaglobin. D, GATA3).
FISH and FINAL DIAGNOSIS