Dedifferentiated adenoid cystic carcinoma: a clinicopathologic study of 6 cases.
Dedifferentiated adenoid cystic carcinomas are a recently defined, rare variant of adenoid cystic carcinomas characterized histologically by two components: conventional low-grade adenoid cystic carcinoma and high-grade "dedifferentiated" carcinoma. We examined six cases and analyzed their clinicopathologic profiles, including immunohistochemical features and p53 gene alterations. The 6 patients (3 men and 3 women) had a mean age of 46.8 years (range, 34-70 y). The mean size of the tumors was 3.5 cm (range, 1.7-6 cm). The submandibular gland, maxillary sinus, and nasal cavity were involved in 2 cases each. Postoperatively, 5 patients had local recurrence and 5 developed metastatic disease. Five patients died of disease at a mean of 33.7 months after diagnosis (range, 6-69 mo), and one other was alive with disease at 60 months. Histologically, the conventional low-grade adenoid cystic carcinoma component of the tumors consisted of a mixture of cribriform and tubular patterns with scant solid areas. The high-grade dedifferentiated carcinoma component was either a poorly differentiated adenocarcinoma (4 cases) or undifferentiated carcinoma (2 cases). Three tumors were studied immunohistochemically. Myoepithelial markers were expressed in low-grade adenoid cystic carcinoma but not in the dedifferentiated component. In 2 cases, diffusely positive p53 immunoreactivity together with HER-2/neu overexpression was restricted to the dedifferentiated component. Loss of pRb expression was demonstrated only in the dedifferentiated component of the 1 other case. The Ki-67-labeling index was higher in the dedifferentiated component than in the low-grade adenoid cystic carcinoma component. Furthermore, molecular analysis of 2 cases demonstrated the loss of heterozygosity at p53 microsatellite loci, accompanied by p53 gene point mutation, only in the dedifferentiated carcinoma component of 1 case, which was positive for p53 immunostaining. These results indicate that dedifferentiated adenoid cystic carcinoma is a highly aggressive tumor. Because of frequent recurrence and metastasis, the clinical course is short, similar to that of adenoid cystic carcinomas with a predominant solid growth pattern. Limited evidence suggests that p53 abnormalities in combination with HER-2/neu overexpression or loss of pRb expression may have a role in dedifferentiation of adenoid cystic carcinoma.
Nagao
Toshitaka
T
Division of Anatomic Pathology, Mayo Clinic, Rochester, Minnesota 55905, USA.
Gaffey
Thomas A
TA
Serizawa
Hiromi
H
Sugano
Isamu
I
Ishida
Yasuo
Y
Yamazaki
Kazuto
K
Tokashiki
Ryoji
R
Yoshida
Tomoyuki
T
Minato
Hiroshi
H
Kay
Paul A
PA
Lewis
Jean E
JE
D000328:Adult; D000368:Aged; D001483:Base Sequence; D003528:Carcinoma, Adenoid Cystic / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D002454:Cell Differentiation; D004252:DNA Mutational Analysis; D004273:DNA, Neoplasm / Q000737:chemistry / Q000235:genetics; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007633:Keratins / Q000032:analysis; D019656:Loss of Heterozygosity; D008297:Male; D008875:Middle Aged; D018396:Mucin-1 / Q000032:analysis; D009154:Mutation; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000032:analysis; D009418:S100 Proteins / Q000032:analysis; D016019:Survival Analysis; D016159:Tumor Suppressor Protein p53 / Q000032:analysis / Q000235:genetics
D004273:DNA, Neoplasm; D007633:Keratins; D018396:Mucin-1; D018719:Erb-b2 Receptor Tyrosine Kinases; D009418:S100 Proteins; D016159:Tumor Suppressor Protein p53