Resident Program - Case of the Month

Clinical History:

A 44-year-old male presents with a two-year history of swelling in the right jaw, which was previously treated with hot compresses and antibiotics with some immediate improvement. For two months prior to presentation, the right jaw mass/swelling grew noticeably larger.

Imaging and Biopsy History:

An ultrasound of the neck was performed showing a hypoechoic mass in the right parotid gland, which was later confirmed on MRI as a 2.3 cm circumscribed mass in the inferior aspect of the right parotid gland.  A biopsy was performed and read as acinic cell carcinoma.

Pathologic findings:

Microscopic examination of the parotid mass reveals the tumor is circumscribed, lobulated, with fibrous septa and composed of papillary-cystic structures with copious eosinophilic luminal secretions. The tumor cells have round to oval nuclei, granular to eosinophilic cytoplasm and occasional prominent nucleoli.  Immunohistochemistry was performed which showed the following:

S100: Positive
Mammaglobin: Positive

Figure 1: H&E from embedded specimen (40X magnification)

Figure 2: H&E from embedded specimen (100X magnification)

Figure 3: S100 from embedded specimen (40X magnification)

Figure 4: Mammaglobin from embedded specimen (40X magnification)