Dedifferentiation in low-grade mucoepidermoid carcinoma of the parotid gland.
Mucoepidermoid carcinoma (MEC), a common malignant salivary gland neoplasm, is generally divided into low-, intermediate-, and high-grade types according to the histologic features. To our knowledge, the present report describes the first case of dedifferentiation occurring in a low-grade MEC. A 55-year-old man presented with a biphasic neoplasm of the right parotid gland composed of low-grade MEC and dedifferentiated high-grade anaplastic undifferentiated carcinoma. Immunohistochemically, carcinoembryonic antigen expression was restricted to the low-grade MEC portion. The Ki-67-labeling index was higher in the dedifferentiated component than in the low-grade component. On image cytometric analysis, the low-grade MEC was diploid, whereas the dedifferentiated carcinoma was aneuploid. Although the patient was alive 10 years after the initial diagnosis, the tumor has recurred twice, at 3 months and 7 months after the initial resection. It is important to recognize that dedifferentiation can occur in a low-grade MEC, similar to other low-grade salivary gland carcinomas.
Nagao
Toshitaka
T
Division of Anatomic Pathology, Mayo Clinic, Rochester, MN 55905, USA.
Gaffey
Thomas A
TA
Kay
Paul A
PA
Unni
Krishnan K
KK
Nascimento
Antonio G
AG
Sebo
Thomas J
TJ
Serizawa
Hiromi
H
Minato
Hiroshi
H
Lewis
Jean E
JE
D000782:Aneuploidy; D014408:Biomarkers, Tumor / Q000378:metabolism; D002272:Carcinoembryonic Antigen / Q000378:metabolism; D002277:Carcinoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D018277:Carcinoma, Mucoepidermoid / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D002471:Cell Transformation, Neoplastic; D003131:Combined Modality Therapy; D004273:DNA, Neoplasm / Q000032:analysis; D006801:Humans; D019044:Image Cytometry; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D009378:Neoplasms, Multiple Primary; D010307:Parotid Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*
D014408:Biomarkers, Tumor; D002272:Carcinoembryonic Antigen; D004273:DNA, Neoplasm; D019394:Ki-67 Antigen