Li et al. Diagnostic Pathology 2012, 7:89 http://www.diagnosticpathology.org/content/7/1/89 CASE REPORT Open Access A noninvasive mucinous cystic neoplasm with intermediate-grade dysplasia of the pancreas and extensive squamous metaplasia: a case report with clinicopathological correlation Peifeng Li1,2†, Yingmei Wang1†, Qingqing Zhang3, Yixiong Liu1, Yang Lv1 and Zhe Wang1* Abstract: Squamous metaplasia presenting in noninvasive mucinous cystic neoplasm (MCN) of the pancreas is extremely rare. We described a case of 39-year-old Chinese female with a 5-year history of a slow growing mass in the left upper abdomen and an 18-month history of surgical incision exudation. The patient underwent cystojejunostomy, laparotomy and distal pancreatectomy consecutively because of the initial diagnosis of “pancreatic cyst”. The histological section showed columnar mucin-producing epithelium formed small papillary projections and extensively visible squamous metaplasia. Therefore the diagnosis of “noninvasive MCN with intermediate-grade dysplasia of the pancreas and extensive squamous metaplasia” was made finally. The squamous component of the pancreas may be derived from pluripotent stem cells, and may be in association with cystojejunostomy. Virtual slides: The virtual slide(s) for this article can be found here http://www.diagnosticpathology.diagnomx.eu/ vs/1322364365718540 Keywords: Mucinous cystic neoplasm, Squamous metaplasia, Pancreas, Immunohistochemistry Background extensive squamous metaplasia. In addition, we discuss the Mucinous cystic neoplasm (MCN) is a rare exocrine pathogenesis of squamous metaplasia and its clinicopatho- pancreatic tumor that can be classified into four histo- logical correlation. pathological types [1]: noninvasive MCN with low-grade, intermediate-grade or high-grade dysplasia and invasive Case presentation MCN. MCN is composed of columnar mucin-producing Clinical history epithelial layers supported by a distinctive ovarian-type A 39-year-old Chinese female was referred to our stroma. Typically, MCN occurs almost exclusively in the hospital with a 5-year history of a slow growing mass in body and/or the tail of the pancreas in perimenopausal the left upper abdomen and an 18-month history of sur- women and shows no communication with the pancreatic gical incision exudation. The painless mass was found ductal system. Extensive squamous metaplasia presenting incidentally with an initial diagnosis of pancreatic cyst in noninvasive MCN of the pancreas is extremely rare, al- 5 years previously, and the palliative bypass procedure of though focal squamous metaplasia of the pancreatic ductal cystojejunostomy was performed. However, due to the columnar cells can be observed in cases with inflammation increasing size of the mass, the patient underwent a [2].Inthisreport,wedescribeauniquecaseofnoninvasive laparotomy 2 years later. This revealed a pancreatic MCN with intermediate-grade pancreatic dysplasia and tumor which was inoperable because of the major adhe- sion surrounding the neoplasm, stomach, greater * Correspondence: [email protected] † omentum, mesentery and abdominal wall. Some of the Equal contributors anastomotic stoma tissue was excised for pathological 1Department of Pathology, State Key Laboratory of Cancer Biology, Xijing Hospital and School of Basic Medicine, Fourth Military Medical University, examination, and a diagnosis of noninvasive MCN with Xi’an, Shaanxi 710032, People's Republic of China intermediate-grade dysplasia was made. After 18 months, Full list of author information is available at the end of the article © 2012 Li et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Li et al. Diagnostic Pathology 2012, 7:89 Page 2 of 5 http://www.diagnosticpathology.org/content/7/1/89 the surgical incision began to produce exudate. On The specimen that was resected at the anastomotic admission to hospital, physical examination revealed a stoma 3 years previously showed two distinct components: single, deep-seated, painless mass and two incisional an inner epithelial layer and an outer cellular ovarian-type sinuses with exudation in the left upper abdomen, stromal layer. The columnar mucin-producing epithelium without tenderness or muscular tension. Laboratory with pseudopyloric-type intracellular mucin and goblet investigations were unremarkable, and serum levels of cells formed small papillary projections – local pseudos- carbohydrate antigen 19–9 and carcinoembryonic anti- tratifications with crowding of slightly enlarged nuclei that gen were within normal ranges. Abdominal ultrasonog- are oriented perpendicular to the basement membranes. raphy and computer tomography scan revealed a The columnar cells with bland uniform histological pat- 7.8 cm × 7.3 cm, heterogeneous hypoechoic or low- tern and minor architectural atypia, were characterized by density mass with poorly defined margins in the tail basally located nuclei and abundant supranuclear mucin region of the pancreas, compressing other adjacent which was positive for periodic acid Schiff with diastase organs. The mass was composed of several large loculi and Alcian blue stains. Crypt-like invaginations were with an irregular thickening of the cyst wall and papil- found focally (Figure 2A). The ovarian-type stroma, char- lary excrescences projecting into the cystic cavity acteristic subepithelial tissue, was composed of densely (Figure 1). Splenomegaly was also found. The patient packed spindle-shaped cells with elongated nuclei and underwent a distal pancreatectomy and splenectomy, sparse cytoplasm. Hypocellular and hyalinized connective during which a pseudo-encapsulated cystic mass adher- tissue was present in variable amounts accompanied by ing to the greater curvature of stomach and distal duo- focal lymphocytic infiltration. In addition to the typical denum was observed. The pancreatic parenchyma in the features of MCN as discussed above, there were some un- region of the cyst was completely atrophied, and the pre- usual findings, including extensive pronounced squamous viously performed anastomosis was obliterated. After an metaplasia and an obviously decreased stroma in the uneventful postoperative recovery, the patient remained complete resection specimen (Figure 2B). Squamous epi- symptom-free without recurrence during the 14-month thelium combined with the top glandular epithelium follow up. excreting mucin. The stratified squamous epithelium formed papillary excrescences with sparse hyalinized fibro- Pathologic Findings vascular stromal cores that protruded into cysts. The The resected neoplasm measuring 7.8 cm × 7.3 cm × 6.5 cm tumor-to-stromal interfaces were smooth with no invasion presented as a round mass with a fibrous pseudocapsule of by the tumor cells. The squamous epithelium in the basal variable thickness. In cross-section, the specimen revealed a layer exhibit moderate pleomorphism and contain large multilocular tumor with cystic spaces ranging in size from hyperchromatic nuclei with a high nucleus to cytoplasm a few millimeters to 1.3 centimeters in diameter, and con- ratio, and mitotic figures are more abundant than usual, taining grey–tan cloudy gelatinous material. The internal but they never reached the level of that seen in carcinoma. surface of the lumina showed multiple papillary projections The abundant cytoplasm was mostly eosinophilic but oc- and mural nodules. The spleen was intumescent and free of casionally clear. Cytoplasmic borders between tumor cells tumor invasion. were distinct. Intercellular bridges were easily identified in the vast majority of tumor cells, and keratinization was not a prominent feature. Abundant ectatic vessels and focal neutrophils and eosinophils were observed in the rare stroma of the glandular element region. The tumor has a relatively well-demarcated pushing border. In terms of immunohistochemistry (IHC), the epithelial component with squamous differentiation was strongly immunoreactive with high molecular weight cytokeratin (HCK, 34βE12) and CK5/6 (Figure 3A), while the glandu- lar epithelial cells were strongly positive for low molecu- lar weight CK (LCK, 35βH11) (Figure 3B). CK14 was expressed in some basal cells, but not in all of the squa- mous epithelium (Figure 3C). Some cells in the micropa- pillary proliferation architectures were immunoexpressed with CK20 (Figure 3D), while both squamous epithelium Figure 1 Abdominal CT scan. The tumor showing a and glandular epithelium were negative for CK20. The heterogeneous multiloculated cystic mass with low density in the expression of P63 was diffusely positive for the squamous tail of the pancreas (white arrow), compressing the adjacent organs. cells with a tendency for intense positivity in the basilar Li et al. Diagnostic Pathology 2012, 7:89 Page 3 of 5 http://www.diagnosticpathology.org/content/7/1/89 Figure 2 Histopathology finding of tumor. (A) The hyperplastic columnar epithelium characterized by basally located nuclei forming small papillary projections with crowding of slightly enlarged nuclei in the stoma tissue sample. Crypt-like invaginations can be found focally (H&E, 100×). (B) Foci of squamous metaplasia and the glandular element are present in the neoplasm. Squamous cells show slight or moderate nuclear hyperchromasia, enlargement and pleomorphism