Am J Surg Pathol  2001 Jan;25(1):26-42 

Colloid (mucinous noncystic) carcinoma of the pancreas.

Adsay NV, Pierson C, Sarkar F, Abrams J, Weaver D, Conlon KC, Brennan MF,
Klimstra DS.

Department of Pathology, Karmanos Cancer Institute, Harper Hospital, Wayne State
University School of Medicine, Detroit, Michigan 48201, USA.
adsayv@med.wayne.edu

In the past, colloid (mucinous noncystic) carcinoma (CC) of the pancreas had
been included under the category of ordinary ductal adenocarcinoma, a tumor with
a dismal prognosis, or was frequently misdiagnosed as mucinous
cystadenocarcinoma. The clinicopathologic features of CC have not yet been well
characterized, because most cases on record have been parts of studies on either
mucinous cystic neoplasms (MCN) or intraductal papillary mucinous neoplasms
(IPMN), with which colloid carcinomas are frequently associated. To determine
the clinicopathologic characteristics of CC, 17 pancreatic tumors composed
predominantly (>80%) of CC (defined as nodular extracellular mucin lakes with
scanty malignant epithelial cells) and in which the invasive carcinoma measured
larger than 1 cm were studied. Ten of these were originally classified as
mucinous ductal adenocarcinoma and four as mucinous cystadenocarcinoma. The mean
age of the patients was 61 years; 9 were men and 8 were women. The mean size of
the CC was 5.3 cm (range, 1.2-16 cm). In more than half of the patients, CC
represented the invasive component of an IPMN (in nine cases) or MCN (in one
case). The tumors were composed of well-defined pools of mucin with sparse
malignant cells in various patterns of distribution. Signet-ring cells floating
in the mucin (but not as individual cells infiltrating stroma, a characteristic
finding of signet-ring cell adenocarcinomas) were commonly identified and were
prominent in five cases. Perineurial invasion was noted in six cases and
regional lymph node metastases in eight. Mutation in codon 12 of the k-ras gene
was detected in only 4 of 12 cases studied and p53 mutation in 2 of 9.
Immunohistochemical and histochemical mucin stains suggested luminalization of
the basal aspects of the cells. Five-year survival was 57%. At an overall mean
follow up of 57 months, 10 patients were alive with no evidence of disease
(median, 79 mos), including four with lymph node metastasis, three others with
perineurial invasion, and another with vascular invasion. Four patients died of
disease (18, 18, 25, and 26 mos), and three died of thromboembolism (with
persistent disease) at 2, 5, 10 months. All seven patients who died with or of
tumor had undergone incisional biopsy of the tumor either before the operation
or intraoperatively, whereas none of the patients who were alive had incisional
biopsy. When compared with 82 cases of resectable ordinary ductal adenocarcinoma
on whom follow-up and staging information was complete, it was found that the
patients with CC present with larger tumors (p = 0.03) but lower stage (p =
0.01). The prognosis of CC is significantly better: 2-year and 5-year survival
are 70% versus 28% and 57% versus 12%, respectively (p = 0.001). In conclusion,
pancreatic CC may occur with or without an identifiable IPMN and MCN component,
and should be distinguished from mucinous cystadenocarcinoma, ordinary ductal
adenocarcinoma, and signet-ring cell adenocarcinoma. CC of the pancreas is
associated with a significantly better prognosis than ordinary ductal
adenocarcinoma. In addition to its distinctive morphologic and clinical
characteristics, CC of the pancreas also appears to have a low incidence of
mutation in codon 12 of the k-ras gene. In cases with a clinical suspicion of
colloid carcinoma, the possibility that an incisional biopsy may contribute to
thromboembolic complications or even dissemination of the tumor may need to be
considered. The luminalization of the basal aspects of the tumor cells may be
the cause of stromal mucin accumulation that characterizes colloid carcinoma and
may act as a containing factor.

PMID: 11145249 [PubMed - indexed for MEDLINE]