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Findings: US showed abnormal mass in the left kidney. Further examination showed large abnormal mass extending from region of the pancreatic tail up towards the left hemidiaphragm, involving the spleen. There was also a mass in the right lobe of the liver. CT of the abdomen and pelvis confirmed the US findings, and showed definite involvement of the tail of the pancreas.
DDx included metastatic pancreatic, renal, gastric, and endometrial cancers, in addition to lymphoma. Percutaneous needle Bx under CT guidance of the liver metastasis was performed.
Diagnosis: Squamous Cell Carcinoma of the Pancreatic Duct, with mets to the spleen, left kidney, and liver.
Discussion:
Pancreatic Ductal Neoplasms:
Ductal Adenocarcinoma comprises 75-90% of all pancreatic
malignancies. Other Duct Cell cancers account for up to 4%
of pancreatic malignancies. Varieties include Mucinous or
Colloid, Squamous, Adenosquamous, Pleomorphic Large Cell,
and Microadeno.
Both Adeno and Squamous types tend to occur in older individuals (60-80yrs), present with disseminated disease (95%), and respond poorly to chemotherapy and XRT; one-year survival for Squamous Cell CA is 4.8%.
Like Adenocarcinoma, Squamous Cell type has predilection for the pancreatic head (involved in 73% of cases). Also, calcification is uncommon in both types (<2%).
Cystic Squamous Cell cancers of the pancreatic duct are quite rare. When they do occur, they may show communication with the pancreatic duct on ERCP. When cystic, the DDx includes: Cystadenoma/Cystadenocarcinoma, Leiomyosarcoma, Rhabdomyosarcoma, Choriocarcinoma, and Pseudocyst (which itself may coexist with a pancreatic carcinoma).
Etiology:
Uncertain. There may be squamous metaplasia of ductal
epithelium - perhaps due to chronic irritation or
inflammation - with malignant degeneration. Squamous
metaplasia of an existing adenocarcinoma is another theory -
which may account for the Adenosquamous variant.
Imaging:
US and CT have both proven to be valuable in assessing
tumor resectability. Unresectable criteria include: tumor
>3cm in size and contiguous with gland surface or adjacent
structures (such as duodenum, SMA); Extracapsular extension;
invasion of vessels or adjacent organs; Distant mets;
ascites.
In a study on the efficacy of ultrasound in assessing the resectability of pancreatic cancers, Campbell et al found NO lesions that proved to be resectable at surgery that they had deemed unresectable by preoperative US; however, 37% of tumors deemed resectable by US actually proved to be so at surgery.
Therefore, US proved to be better at determining unresectability than it was at determining resectability. CT seems to share this limitation.
References:
1. "Pancreatic Neoplasms: How Useful Is Evaluation with
US?"; Joan P. Campbell, et al; Radiology, 1988; 167:341-344.
2. "Pancreatic Ductal Adenocarcinoma: Diagnosis and Staging
with Dynamic CT"; Patrick C. Freeny, et al; Radiology 1988; 166:125-133.
3. "Computed Tomography Findings in Squamous Cell Carcinoma
of the Pancreas"; Laurie L. Fajardo, et al; The Journal
of Computed Tomography 1988; 12:138-139.
4. "Squamous Cell Carcinoma of the Pancreas: Report of an
Unusual Case and Review of the Literature"; Kevin L. Beyer,
et al; Digestive Diseases and Sciences, Vol.37, No.2
(Feb.1992):312-318.
5. "Cystic Masses of the Pancreas"; Pablo R. Ros, et al;
RadioGraphics 1992; 12:673-686.
6. "Squamous Cell Carcinoma of the Pancreas: Report of a
Case and Review of ERCP Findings"; V.G. Koduri, et al;
Endoscopy 1994; 26:333-4.
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