A case report of primary pancreatic lymphoma revealed by an acute pancreatitis

Abstract

Introduction

Primary pancreatic lymphoma (PPL) is a rare malignancy. Diffuse large B-cell lymphoma is the predominant subtype, often affecting the pancreatic head in elderly males. Due to its rarity and nonspecific symptoms, PPL is frequently misdiagnosed, leading to unnecessary surgeries. This case report discusses the diagnosis and management of PPL in a 47-year-old female, emphasizing the challenges in its identification.

Case presentation

A 47-year-old female with no medical history presented with severe epigastric pain and jaundice. Diagnosed initially as acute pancreatitis. The abdominal CT scan showed a tumor in the head of the pancreas suggesting pancreatic adenocarcinoma invading the vessels, making it minimally borderline. However, due to the presence of large intra- and retroperitoneal lymph nodes casting doubt on the diagnosis, we further investigated with an MRI and Endoscopic Ultrasound with fine-needle aspiration, which ruled out adenocarcinoma and confirmed a pancreatic diffuse large B-cell lymphoma. The patient underwent chemotherapy with CHOP, showing significant improvement after six cycles.

Discussion

Primitive pancreatic lymphoma (PPL) is a rare form of non-Hodgkin lymphoma, often mimicking other pancreatic diseases. B-cell lymphomas, especially diffuse large B-cell lymphoma (DLBCL), are common in PPL. Diagnostic criteria include the bulk of disease in the pancreas, no splenic or hepatic involvement, and normal white blood cell count. Imaging modalities aid in diagnosis, but histopathological evaluation is essential. Treatment options include chemotherapy, radiation therapy, and surgery, with rituximab-based regimens being common for DLBCL.

Conclusions

B-cell pancreatic lymphoma poses diagnostic challenges due to nonspecific symptoms. A definitive diagnosis requires histopathological evidence, often obtained through minimally invasive procedures like endosonography-guided biopsy. Treatment involves chemotherapy, immunotherapy, and radiation, with early detection correlating with improved outcomes. Surgery's role is limited due to the diffuse nature of the disease. This case underscores the importance of considering PPL in the differential diagnosis of pancreatic masses, especially in atypical clinical presentations.

Highlights

• •The presented case emphasizes the diagnostic challenges posed by PPL and underscores the importance of considering it in the differential diagnosis of pancreatic masses.
• •The discussion emphasizes the significance of histopathological evidence for an accurate diagnosis, particularly in the context of this rare pancreatic malignancy.
• •This case highlights the importance of tailoring treatment approaches based on histological subtypes and the diffuse nature of the disease.

1. Introduction

Primary pancreatic lymphoma (PPL) is an uncommon malignant tumor, constituting only 0.2 % of pancreatic neoplasms and 0.1–0.5 % of malignant lymphomas [1]. The most prevalent subtype is diffuse large B-cell lymphoma, with a predilection for the pancreatic head, particularly in elderly males [[1], [2], [3]]. Owing to its infrequency and the nonspecific nature of its symptoms, primary pancreatic lymphoma is frequently misidentified as pancreatic adenocarcinoma or other pancreatic neoplasms, leading to unnecessary surgical interventions [4]. This article presents a case report involving a 47-year-old female patient diagnosed with primary pancreatic lymphoma. Adhering to SCARE guidelines [5], this case report underscores the significance of considering primary pancreatic lymphoma as a potential diagnosis for pancreatic masses, particularly in cases with atypical clinical presentations.

2. Case presentation

A 47-year-old female without any medical or surgical history presented to the emergency department complaining of intense transfixing epigastric pain radiating around the waist, of sudden onset, not relieved by analgesics and progressive jaundice evolving continuously. During the questioning, there was no history of similar episodes or biliary colic. Physical examination revealed tenderness in the epigastric region and cutaneous-mucous jaundice. There was no palpable gallbladder on abdominal palpation.

The rectal examination found discolored stools. Laboratory assessments disclosed a lipase level of 1300 U/L. The diagnosis of acute pancreatitis was established based on transfixing epigastric pain and an elevation of lipase levels three times the normal range. The rest of the biological assessment revealed an abnormal liver function tests, including a total bilirubin level of 160 μmol/L, primarily direct, alkaline phosphatase level of 745 U/L, and gamma-glutamyl transferase (GGT) level of 1023 U/L, leading to the diagnosis of acute pancreatitis. To determine signs of radiological severity, pancreatitis, an abdominal CT scan was performed on day 7 of symptom onset, revealing stage C pancreatitis along with a tumoral process measuring approximately 6 cm in diameter in the pancreatic head with invasion of the mesenteric vessels and dilation of the biliary and the Wirsung duct without upstream pancreatic atrophy. Additionally, hypodense areas suggestive of intra- and retroperitoneal lymphadenopathy were observed (Fig. 1). The possibility of borderline pancreatic adenocarcinoma was considered, prompting a pancreatic MRI due to diagnostic uncertainty. The MRI unveiled a pancreatic mass exhibiting T1 hypointensity, T2 hypointensity, and restricted diffusion, indicative of a hypercellular tumor. The imaging also showed retroperitoneal extension and vascular invasion, raising suspicion of pancreatic lymphoma (Fig. 2). Subsequent diagnostic procedures included an endoscopic ultrasound (Fig. 3) guided fine-needle aspiration and biopsy, revealing B-cell pancreatic lymphoma. Immunohistochemical analysis of the biopsy confirmed the diagnosis of diffuse large B-cell lymphoma (DLBCL). This large B-cell lymphoma demonstrated sub-diaphragmatic involvement. The extension assessment did not find any other peripheral or intrathoracic lymph nodes. A PET scan was not performed due to its unavailability. The pre-therapeutic assessment showed a high LDH level of 400 U/L and negative viral serologies (hepatitis, EBV, HIV). Treatment involved chemotherapy based on CHOP, and after six cycles, the patient exhibited significant improvement in symptoms, along with a reduction in the size of the pancreatic mass on follow-up imaging. The patient is currently under regular follow-up care, including surveillance imaging and blood work, to monitor for any signs of recurrence.

Fig. 1.

Abdominal CT scan (with contrast medium injection) showing a tumoral process measuring approximately 6 cm in diameter located in the pancreatic head and hypodense areas associated with intra- and retroperitoneal lymphadenopathy.

Fig. 2.

Images of pancreatic MRI revealing a large pancreatic tissue process with retroperitoneal extension and vascular invasion suggestive of pancreatic lymphoma: a. T1 hypo intensity b. T2 hypointensity. c. restricted diffusion.

Fig. 3.

Images of Echoendoscopic Ultra Sound showing the pancreatic mass.

3. Discussion

Primitive pancreatic lymphoma (PPL) represents a rare subtype of non-Hodgkin lymphoma, constituting merely 0.2 % of all pancreatic tumors and a mere 0.1 % of malignant lymphomas [1,3]. Predominantly, B-cell lymphomas emerge as the most prevalent type of pancreatic lymphoma, with high-grade diffuse large B-cell lymphoma (DLBCL) being the foremost subtype [6]. Behrns et al. established diagnostic criteria for PPL, stipulating that the mass must be within the pancreas, with involved lymph nodes confined to the peri-pancreatic region. Additionally, there should be no splenic or hepatic involvement, no palpable superficial lymphadenopathy, no mediastinal nodal enlargement on chest radiography, and a normal white blood cell count [6]. Our patient aligns with these criteria. More recently, the World Health Organization (WHO) has refined diagnostic criteria, emphasizing that the bulk of the disease must be situated in the pancreas, and although adjacent lymph node involvement and distant spread may occur, the primary clinical presentation must involve the pancreatic gland [7]. While PPL can manifest at any age, it predominantly affects elderly individuals, with a male prevalence [2]. Epigastric pain is the most common symptom associated with PPL, although other clinical findings such as systemic symptoms (fever, night sweats, and weight loss), jaundice, pancreatitis, and gastric or duodenal obstruction can be nonspecific [3,5]. This diversity in presentation often leads to challenges in diagnosis, as PPL can mimic other pancreatic diseases, notably pancreatic adenocarcinoma.

Imaging modalities such as CT, MRI, and endoscopic ultrasound (EUS) play crucial roles in diagnosis, but a definitive confirmation necessitates histopathological evaluation via biopsy. Ultrasonography (US) is widely used for a rapid evaluation of pancreas size, borders, echostructure, and vessels. Common findings include parenchymal enlargement, focal or diffuse, with lower echogenicity. On CT, primary pancreatic lymphoma (PPL) appears as a large solid lesion potentially involving the entire gland, with lower contrast enhancement than healthy pancreas. Fat stranding in the peri-pancreatic region is typical, and vascular encasement can be observed without vessel wall irregularities [3,8]. MRI is an alternative to CT, especially when inconclusive or to avoid radiation exposure in younger patients. Involved parenchyma exhibits lower signal intensity on T1-weighted images and higher signal on T2-weighted images. Diffusion-weighted sequences show high sensitivity to depict lymphomatous tissue and lymph nodes. PET-CT is recommended to assess the metabolic activity of the primary neoplasm and detect involved lymph nodes throughout the body [[2], [3], [4]]. Vascular involvement is infrequent but may rarely be observed [8]. CA19–9 level elevation is rare in PPL, and an increased LDH level is not a requisite for diagnosis [9]. Histological evidence is indispensable for diagnosing primary pancreatic lymphoma, typically obtained through minimally invasive approaches like transparietal or endoscopic biopsy. In fact, more than half of the reported cases in a meta-analysis by Facchinelli et al. relied on noninvasive procedures, such as transcutaneous biopsy (30.3 %), endoscopic biopsy (17.4 %), and fine-needle aspiration (FNA) (14.8 %) [3]. EUS-guided tissue acquisition (EUS-TA) emerges as a valuable technique, enhancing diagnostic accuracy by enabling the collection of tissue samples [10]. Treatment options for pancreatic lymphoma encompass chemotherapy, radiation therapy, and surgery. The optimal treatment, as indicated in Facchinelli et al.'s 2021 meta-analysis, is contingent upon the histological subtype. R-CHOP chemotherapy, incorporating rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone, is a common regimen for DLBCL, the most prevalent subtype [3,5]. In specific cases of positive CD20 in diffuse large B-cell lymphoma, rituximab is added to the regimen, enhancing the remission rate [5]. Although the combination of radiotherapy and chemotherapy has been employed in some cases, its efficacy remains unproven [11]. The role of surgery in managing pancreatic lymphoma is limited due to the diffuse nature of the disease, often involving adjacent organs. In a meta-analysis by Facchinelli et al., 26.1 % of patients underwent potentially unnecessary surgical treatment [3]. The prognosis for these patients undergoing unnecessary surgery was bleak. Indeed, the overall survival for patients who underwent surgery for undiagnosed pancreatic lymphoma preoperatively was reduced to 11 months [3–19], according to the same meta-analysis in 2021, whereas it was 34.7 months [5–192] with immunotherapy [3].

4. Conclusions

B-cell pancreatic lymphoma is a rare malignancy that can present with nonspecific symptoms and can be challenging to diagnose. A biopsy is required for a definitive diagnosis, and treatment options include chemotherapy, immunotherapy and radiation therapy. Early detection and treatment can lead to improved outcomes for patients with this rare malignancy.

Patient consent

Written informed consent was obtained from the patient to publish this case report and accompanying images. On request, a copy of the written consent is available for review by the Editor-in-Chief of this journal.

Provenance and peer review

Not commissioned, externally peer-reviewed.

Ethical approval

Ethical approval is exempt/waived at our institution.

Funding

No funding.

Author contribution

All the authors participated in the manuscript and validated the final version of the manuscript.

Guarantor

Mohamed Ali Chaouch.

Research registration number

Not applicable.

Conflict of interest statement

The authors declare no competing interest.