V. Adsay et al., Foamy gland pattern of pancreatic ductal adenocarcinoma - A deceptively benign-appearing variant, AM J SURG P, 24(4), 2000, pp. 493-504
Citations number
24
Categorie Soggetti
Research/Laboratory Medicine & Medical Tecnology","Medical Research Diagnosis & Treatment
Pathologic diagnosis of pancreatic adenocarcinoma is frequently a challenge
, particularly in small biopsies, frozen sections, and in metastatic foci.
Here we report a deceptively benign-appearing and morphologically distincti
ve pattern of ductal adenocarcinoma with prominent microvesicular cytoplasm
, giving the cells a foamy appearance similar to that described in the pros
tate (Am J Surg Pathol 1996;20:419). This variant, which we refer to as foa
my gland pattern (FGP), was frequently misdiagnosed in frozen sections or b
iopsies and its pathologic stage underestimated in surgical specimens. Hist
ologically, the diagnostic features were: (1) white and crisply foamy, "mic
rovesicular" cytoplasm; (2) often basally located and compressed, hyperchro
matic nuclei reminiscent of endocervical glands (and so-called "adenoma mal
ignum") or gastric foveolar glands; (3) irregular nuclear contours forming
wrinkled (raisinoid) nuclei in some areas; and (4) a distinctive chromophil
ic condensation of the cytoplasmic material in the luminal aspect of the ce
lls forming a brush border-like zone (BLZ). Histochemically, this BLZ was p
ositive for mucicarmine, alcian blue, and high iron diamine, but not PAS. T
he remainder of the cytoplasm was negative for all these stains. In contras
t, benign mucinous ducts, which constitute the major differential diagnosis
, had more homogeneous acidophilic cytoplasm, lacked BLZ, and showed cytopl
asmic staining with PAS. Immunohistochemically, the tumor cells were diffus
ely and strongly positive for CEA and cytokeratin 8 whereas B72.3 staining
was focal and weak. MUC1 staining was largely confined to the BLZ. MUC2 was
negative. P53 staining was detected in 16 of the 20 cases studied and was
strong and diffuse in five. K-ras mutation was detected in 6 of 8 cases stu
died. The clinical findings in the 20 patients in this study (4 pure and 16
mixed with usual ductal carcinoma) did not appear to differ significantly
from those of ordinary ductal adenocarcinoma of the pancreas. Eleven patien
ts were men and nine were women; the mean age was 62 years and the mean tum
or size was 4.4 cm. Follow-up information was available in 17 patients of w
hom 7 were alive at an average follow up of 23 months (range, 7-104 mos), a
nd 10 were dead of disease at a median follow up of 15 months (range, 4-42
mos). The median survival of the four patients with pure FGP was 18 months.
The median survival did not appear to be significantly longer than that of
the patients with resectable ordinary ductal adenocarcinoma in the authors
' experience (109 patients, median survival of 12 mos, p = 0.48). In conclu
sion, foamy gland pattern of invasive pancreatic ductal carcinoma is morpho
logically distinctive and is prone to misdiagnosis as a benign process. The
pathologic stage is often underestimated as a result of the lack of its re
cognition and misinterpretation as mucinous ducts. Careful attention to its
microscopic features is adequate for accurate diagnosis. Histochemical and
immunohistochemical stains are useful in confirming the diagnosis of malig
nancy in challenging cases.