Case report of a pancreatic squamoid cyst

Squamoid cyst of pancreatic ducts: A case report

The term squamoid cyst of pancreatic ducts (SCOP) has been proposed recently, and it is a very rare benign lesion. We report a case of SCOP in a patient who underwent laparoscopic distal pancreatectomy. A 51-year-old woman presented with a pancreatic cystic lesion (3.3 cm) as an incidental finding on abdominal ultrasonography. A computed tomography scan showed a well-defined cystic lesion in the body of the pancreas with peripheral nodular calcification. Histology showed a unilocular cyst with a thin, fibrotic wall, and it was surrounded by normal-appearing pancreatic tissue. The lining of the cyst was composed of stratified non-keratinized squamous epithelium without significant nuclear atypia. Immunohistochemistry showed positive nuclear p63 expression in the cyst lining. The final diagnosis of SCOP was established. It is important to distinguish SCOPs from mucinous pancreatic cysts that have malignant potential. Preoperative diagnosis of SCOP is still difficult, and further studies are needed to identify specific preoperative characteristics that can accurately distinguish this lesion.

Intraductal papillary squamous neoplasm of the pancreas: Cyto-histologic correlation of a novel entity

We correlate the cytologic and histologic features of a squamous-lined pancreatic cystic lesion with a complex papillary architecture and an associated KRAS mutation, which to our knowledge has not been previously described. A 69 year-old woman presented with intermittent left upper quadrant pain. CT imaging revealed a 1 cm solid lesion in the pancreatic tail with peripheral calcification. Endoscopic ultrasound-guided fine needle biopsy showed a proliferation of epithelial cells with fibrovascular cores. An immunohistochemical stain for p40 was positive in the lesional cells. A distal pancreatectomy revealed a unilocular, cystic, well-circumscribed, soft and friable mass measuring 1.0 × 1.0 × 0.8 cm. Histologically, the cyst was lined by nonkeratinizing stratified squamous epithelium with a complex papillary architecture, filling the cyst lumen. Molecular sequencing revealed a KRAS G12V missense mutation. While the lesion shared some histologic features with the previously described "squamoid cyst of the pancreatic ducts", the complex papillary architecture and presence of a KRAS mutation are unique to the entity we describe herein and we propose the name "intraductal papillary squamous neoplasm of the pancreas." Reporting the cytomorphologic features of this novel entity may help in identification of similar lesions and understanding of the clinicopathologic significance.