Primary squamous cell carcinoma of pancreas in a patient with chronic pancreatitis: A rare case report

Abstract

Primary squamous cell carcinoma of pancreas is a rare malignant neoplasm. It has been reported as case reports only, hence clinical information is limited. Here, we present a case of primary squamous cell carcinoma of pancreas in a 47-year-old female with a background history of chronic pancreatitis. Patient was treated with systemic chemotherapy; however, she did not respond to the treatment protocol. Follow-up CT scan showed increase in the size and extension of the lesion. It is an aggressive tumor and does not respond well to chemotherapy or radiotherapy.

Introduction

Primary squamous cell carcinoma of pancreas is a rare tumor with an incidence of 0.5%-2% of all pancreatic neoplasms [1]. Squamous cells are absent in normal pancreas [2]. Therefore, pathogenesis of this rare entity remains unknown. Squamous metaplasia of pancreatic duct is found in 9%-64% of pancreas, but transformation into squamous cell carcinoma is extremely rare. However, squamous metaplasia of the ductal columnar cell has been reported in the setting of chronic pancreatitis and postpancreatic duct stenting [3,4]. Kim et al. [5] reported the first primary squamous cell carcinoma of pancreas in a patient with chronic pancreatitis in English literature.

Case report

A 47-year-old female presented to our institute with a 2-month history of epigastric pain, radiating to back. Patient also gave the history of chronic pancreatitis since 2 years, for which she underwent Frey's procedure 6 months back. Clinical examination revealed a palpable mass with tenderness in epigastric region. She had a medical history of 5 years of type II diabetes mellitus and was on medication (glimepiride and metformin). Upper GI endoscopy was normal. Abdominal ultrasound revealed atrophied pancreas with heterogeneously hypoechoic mass lesion possibly arising from pancreas. Laboratory investigations showed mildly elevated ALP - 164U/L (normal range 44-147 IU/L) with normal CEA and CA 19.9. Other blood parameters were within normal limits. Plain and contrast-enhanced CT was performed with a 64 slice Philips Brilliance scanner, 80 mL nonionic contrast (ultravist, 370 mg I/Ml) was injected with a rate of 4 mL per second through 18G intravenous cannula. Triphasic CT scan was performed. Non-contrast CT demonstrated an isodense mass (Hounsfield unit [HU] value 38.5) showing intratumoral calcifications. On arterial, portal and delayed phase mass was heterogeneously enhancing with HU values 66.5, 64, and 63, respectively. Mass measuring ∼ 32 × 52 × 40 mm was seen arising from body and tail region of pancreas with internal nonenhancing areas. Adjacent fat stranding was also noted. The lesion was infiltrating the adjacent jejunal loop. Remaining pancreatic parenchyma appeared atrophied. Splenic artery was attenuated in caliber and completely encased by the lesion. No significant peripancreatic or retroperitoneal or mesenteric lymph node was noted. No focal lesion was noted in the liver or spleen (Fig. 1, Fig. 2, Fig. 3). MRI abdomen demonstrated heterogeneously T2 hyper-intense lesion measuring ∼37 × 54 × 45 mm with few nonenhancing areas in the body and tail region of pancreas. The lesion was hyperintense on DWI. No loss of signal intensity could be seen between in-phase and out-of-phase images (Fig. 4). Fine-needle aspiration cytology was performed at our institute and reported as squamous cell carcinoma, which displayed intraparenchymal tumor nest, keratin pearl, and clear cell change. PET-CT showed heterogeneously increased FDG uptake (SUV max 7.19) in the pancreatic region. No evidence of uptake in rest of body suggestive of primary squamous cell carcinoma of pancreas (Fig. 5). Follow-up CT scan, postchemotherapy demonstrated increase in the size and extension of the lesion. It was partially encasing the celiac axis. Splenic artery was severely attenuated in caliber in its entire course. However, SMA was normally visualized (Fig. 6).

Fig. 1.

Noncontrast CT (A) coronal, (B) axial shows homogeneously isodense soft tissue lesion with foci of calcifications within (white long and short arrows).

Fig. 2.

Primary squamous cell carcinoma of pancreas (prechemotherapy): (A) arterial, (B) portal, (C) delayed phase of triphasic CT shows heterogeneously attenuating pancreatic body and tail mass, showing progressive washout on delayed images (long white, short white, black arrows).

Fig. 3.

Primary squamous cell carcinoma of pancreas-axial and coronal arterial phase CT (prechemotherapy): (A, B) the lesion is encasing the splenic artery (long white and black arrows).

Fig. 4.

Primary pancreatic squamous cell carcinoma- axial and coronal MRI abdomen (prechemotherapy): (A, C) heterogeneously T2 hyper-attenuating well-defined lesion in pancreatic body (long white arrow), (B) hyperintense on DWI (long thin arrow), (D, E) no loss of signal intensity between the in-phase (thin black arrow) and out-of-phase images (short white arrow).

Fig. 5.

Primary squamous cell carcinoma of pancreas; (A, B) FDG-PET scan 3D tracer uptake noted in pancreatic region (thin and thick black arrows), (C) fusion image showing uptake in pancreatic region (long white arrow).

Fig. 6.

Primary squamous cell carcinoma of pancreas arterial phase (postchemotherapy), extensions of the lesion: (A) the lesion is abutting the left diaphragmatic crura (long black arrow), (B, C) celiac axis is partially encased by the lesion (short black and thin white arrows), SMA is not involved (white short arrow), (D) tumor is infiltrating the jejunal loop (long white arrow).

Discussion

Primary squamous cell carcinoma of pancreas is a rare malignant tumor. Ntanasis-Stathopoulos et al. described 54 cases throughout the years of 2000-2012 (constituting 0.5%-0.2% of all pancreatic tumors) [6], [7], [8]. Higher mortality rates are seen in locally metastatic or locally advanced disease in squamous cell carcinoma [7]. The disease is aggressive and does not respond well to chemotherapy or radiotherapy [8].

The first case was reported by Lai et al. in 1949 [9]. Baylor and Berg et al. described the incidence of PSCCP as 0.5% of pancreatic carcinoma [10]. In view of this rare entity, squamous cell carcinoma in pancreas is presumed to be metastatic from other primary site, until proven otherwise [3], [4], [5], [6], [7], [8]. Usually, the diagnosis of the disease is made at the advanced stage of the disease. Metastases from other primary malignancy to the pancreas are also rare. In literature, metastases from esophageal carcinoma to the pancreas have been reported [11]. Regional lymph nodes metastases have been reported in few cases [12], [13], [14]. Significant lymph node was not evident in our case. PET-CT revealed no primary lesion elsewhere in the body in our patient. Kodavatiganti et al. [12] utilized PET-CT scan to exclude any primary lesion elsewhere in the body in order to diagnose primary squamous cell carcinoma of pancreas. Surgery is the mainstay treatment of this rare malignancy. In 7 patients who underwent surgery, median survival was 7 months, with a range of 6-16 months [15]. Patients who did not have curative resection, median survival was 3 months [15,17]. Our patient underwent palliative systemic chemotherapy with gemcitabine (1.2 g i/v) and cisplatin (30 mg i/v) for 6 cycles with an interval of 7 days. However, patient did not respond to the treatment. In a case report by Zhang et al. [14], the size of the mass showed no changes even after completion of chemotherapy and the tumor progressed over time. In other studies, combinations of cisplatin with fluorouracil [15] and carboplatin with cisplatin [16] were also used. Etoposide and vinblastine were also mentioned in other studies [15]. The differential diagnosis of SCC of pancreas should include solitary papillary tumor, adenocarcinoma, and endocrine tumors. Solitary papillary tumor are usually large and encapsulated, which shows necrosis, hemorrhage, and cystic changes but do not contain pancreatic ductal dilatation while accompanied by high signal intensity on fat-saturated T2WI [18]. Adenocarcinoma usually presents with ill-defined tumor margin and pancreatic atrophy and ductal dilatation [18]. Peripheral enhancement with new vessel formation or tumor blush pattern of SCC is uncommon in adenocarcinoma [5]. Pancreatic leiomyosarcoma was reported as a well-circumscribed mass with homogeneously or heterogeneously solid cystic lesion with cystic tumor necrosis [19]. These findings however are also found in fibrosarcoma, malignant fibrohystiocytoma, liposarcoma, rhabdomyosarcoma, and malignant hemagiopericytoma [20].

Conclusion

Primary squamous cell carcinoma of pancreas is extremely rare and aggressive; hence, primary squamous cell carcinoma from other primary should be looked for and excluded. It is extremely difficult to make a diagnosis based on imaging; therefore, cytology is needed. In view of this rare entity, squamous cell carcinoma in pancreas is presumed to be metastatic from other primary site, until proven otherwise.

Patient consent

Written informed consent for the publication of this case report was obtained from the patient.