Anaplastic Carcinoma of the Pancreas Appearing with Low Back Pain due to Epidural Spinal Cord Compression: a Case Report

Low back pain (LBP) is one of the most important health conditions that can affect humans with physical and psychosocial changes. Non-specific LBP, defined as self-limiting and whose exact cause cannot be determined, is common among older adults. Lumbar disk herniation should be the first diagnosis that comes to mind in 40–60-year-old patients with clinical findings of radiculopathy with LBP. However, in order not to miss important causes such as malignancy that can cause LBP, the patient’s history should be deepened, and a physical examination should be performed carefully. We present the case of a 53-year-old female patient who applied to our clinic with LBP accompanied by radiculopathy and was diagnosed with anaplastic carcinoma of the pancreas (APC) by biopsy taken from a lesion in the sacral region detected by advanced imaging. APC is rare cancer, and the survival time of the patients is quite short due to its rapid spread and resistance to chemotherapy and radiotherapy. Based on this case, clinicians should evaluate the patient in detail and carefully, perform further imaging when necessary, and discuss the case with musculoskeletal radiologists when there are diagnostic problems, which will reduce the possibility of overlooking the underlying serious causes of LBP.


Introduction
Low back pain (LBP) is one of the most common musculoskeletal complaints encountered in our clinical practice. The complexity in obtainment a definitive diagnosis for most presentations of back pain has given rise to the term "nonspecific low back pain," which is generally considered to be benign and can be managed in a primary care setting. However, some of the patients present with LBP as the initial manifestation of more serious clinical disorders, such as malignancy, spinal fracture, infection, or cauda equina syndrome [1].
LBP with concurrent radiculopathy in between 40-and 60-year-old patients is commonly associated with lumbar disk herniation [2]. However, red flag questioning, full clinical examination, and advanced imaging may enable the clinician to diagnose the underlying primary malignancy in a patient with LBP. Neoplastic epidural spinal cord compression (ESCC) is a relatively common complication of cancer that can cause LBP, mechanical instability of the spine, and potentially irreversible loss of neurologic function [3].
In this study, we describe a rare case of anaplastic carcinoma of the pancreas (ACP) detected by advanced examinations in an elderly patient with worsening LBP and progressive neurological deficit.

Case Presentation
A 53-year-old female patient was admitted to our outpatient clinic with the complaint of pain lasting approximately 40 days and radiating from the lumbar region to the right leg. She had never complained of LBP in her life before. The pain, which was only in the lumbar region at first, worsened gradually and spread to the medial of the right leg and the dorsum of the foot. The pain character was burning and cramping and tended to decrease while at rest. She did not describe a loss of sensation, numbness, or tingling. The pain was achy all day, worsening at night, and scored 9 of 10 on a visual analog scale. She reported that she had difficulty walking for about a week due to severe pain and loss of strength in her right leg. When the patient's history was deepened, she stated that she had fatigue, sometimes night sweats, and a 4-kg loss in the last month. No bowel-or bladder-related symptoms were reported. There was no history of smoking, trauma, or other chronic and systemic disorders. There was no specification about her family story. On physical examination, vital signs were within normal limits. In the musculoskeletal exam, there was mild tenderness in T11-T12 spinous processes. The lumbar range of motion (ROM) was painful and limited at the end of the ROM in all directions. Straight leg raise test, well leg raise test, Patrick FABER, and Braggard's test were positive on the right side for LBP with radiation to the right leg down. The femoral stretch test was negative for both sides. Neurological examinations revealed decreased muscle power for the right hip flexors (Manual Muscle Test (MMT) grade III), right ankle dorsiflexors (MMT grade II), right big toe extensors (MMT grade II), and right ankle plantar flexors (MMT grade IV). Her Achilles reflex at the right leg was grade 0, and sensations at the posteromedial side of the calf and last toe were reduced. Pathological reflexes were absent at both lower extremities.
FIve days after the onset of LBP before applying to us, the patient was evaluated and further investigated by the external medical center neurosurgery clinic, and the noncontrast lumbar spine MRI of the patient at that time was reported as having a right-sided broad-based posterior protrusion at the L2-L3 level and compressing the thecal sac and right L2 nerve root. Gabapentin 900 mg/daily was given in three divided doses, but there was no effect on her LBP. The first lumbar MRI of the patient which was re-examined due to worsening of the patient's symptoms and physical examination findings was not compatible with any lumbar radiculopathies; there was a lesion showing a signal loss in the T10 vertebral body in T1 sequences and a mass lesion showing a signal loss in the right half of the sacrum in T2 sequences (Fig. 1). That is why an anterior-posterior (AP) pelvis radiograph was performed first and showed the right half of the sacrum is observed with increased density and intestinal gases pushed left and caudally at the right pelvic entrance (Fig. 1). The new contrast-enhanced lumbar spine MRI revealed the lesions suspicious for metastasis observed in the previous examination in T10 vertebrae was enlarged and spread to the T11 vertebral body and both pedicles, disrupting the bone integrity of the right side, and compressing the spinal cord from the right and narrowed the right neural foramina from T10 to T12 vertebrae (Fig. 2). Also, there was a large mass in the form of paravertebral muscle invasion up to the level of L4 vertebrae. This mass was destroying the cortex, compressing the S1 right nerve root and reaching 16 × 12 × 6.5 cm in the right half of the sacrum (Fig. 2). Furthermore, heterogeneities in medullary bone marrow Fig. 1 The first MR images of the lumbar spine. a Sagittal T1-weighted image showing a disk protrusion at the L2-L3 level (thin arrow) and a suspicious signal loss in the T10 vertebral body (thick arrow). b Coronal T1-weighted image representing the enhancing mass at the sacroiliac joint level (thick arrow). c AP pelvis radiograph showing intestinal gases pushed to the left and caudally (arrowhead) with a large mass (thick arrow) signaling were observed in T2-T5-T10-T11-T12-L2-L3 and L4 vertebras, right iliac wing, right femoral neck, trochanter major of the left femur, and right superior pubic ramus. These masses demonstrated contrast enhancement.
The patient was referred for an immediate consultation at medical oncology and neurosurgery clinics. F-18 FDG PET/ BT results showed a metastatic soft tissue mass, approximately 10 × 5 cm in size, invading the spinal cord between the T8 and 12 vertebrae levels; another soft tissue mass, approximately 14 × 7 cm in size, destructing the right half of the sacrum; and a hypermetabolic mass lesion at the pancreatic body-tail junction, approximately 2.8 × 2.4 cm in size, primarily compatible with primary pancreatic malignancy. The patient underwent a tru-cut biopsy from the soft tissue mass on the right side of the sacrum. The tumor showed a solid-infiltrative growth pattern with small-medium round cells and focal necrosis areas in histological studies, and along with these findings, it was reported as undifferentiated ACP. Chemotherapy and radiotherapy were started by the oncologist after the biopsy result. After approximately 10 days, the patient applied to the emergency department with complaints of weakness, malaise, fatigue, chest pain, dyspnea, and hemoptysis. Bilateral massive pulmonary thromboembolism was observed in computed tomography angiography. And the patient died on the same day.

Discussion
LBP with concurrent radiculopathy in a mid-50-year-old patient is usually associated with lumbar disk herniation [2]. However, as in this case, causes with worse prognosis of specific LBP should be considered and advanced imaging methods should be used in patients over 50 years of age who present with sudden onset, awaken at night, worsening, and accompanied by neurological deficits, night sweats, and weight loss. The spine can be affected by severe pathologies such as spinal fracture and malignancy. In patients with LBP applying to primary care, between 1 and 4% will have a spinal fracture and in less than 1% malignancy will be the underlying cause [1]. It is important to question the red flags in uncovering the serious underlying causes of the patient presenting with LBP.
ACP is a very rare histologic subtype of pancreatic cancer. In this case, it presented with LBP and was accompanied by clinical findings mimicking radiculopathy. In addition, an important point to be taken from this case is that LBP due to spinal metastases was the initial symptom of ACP. In a retrospective review of the clinical histories of 337 patients with radiologically confirmed spinal epidural metastases, ESCC was the initial manifestation of malignancy in 20% of these patients [4]. At autopsy, vertebral metastases have been described in 25% of gastrointestinal (GI) cancers [5]. Sandhu et al. [6] reported that the histological diagnoses included colorectal cancer (46%), hepatocellular carcinoma (19%), neuroendocrine carcinoma (13%), pancreatic carcinoma (12%), and the other GI cancers (10%). And previous reports have shown the prevalence of the skeletal metastases of pancreatic cancers to range from 5 to 20% [7] ACP or undifferentiated carcinoma is reported to represent only 2 to 7% of all pancreatic cancers [8]. To the best of our knowledge, there are no case reports in the literature with the initial symptom of LBP due to ESCC and diagnosed with ACP.
The patients usually have rapid growth of large tumors and a very poor prognosis when diagnosed with ACP [9]. The clinical features of the ACP are abdominal pain, back Post-contrast axial 3D T1-weighted image confirming the enhancing mass (thick arrow), foraminal involvement (arrowhead), and spinal cord compression (thin arrow). c Coronal STIR image demonstrating a large mass with paravertebral (arrowhead), sacroiliac, and sacral (thick arrow) involvements. Additionally, gluteal denervation edema (thin arrow) is seen in gluteal muscles pain, fatigue, fever, jaundice, body weight loss, and abdominal discomfort according to Hoshimoto et al. [10]. All types of ACPs have poor survival when compared with the invasive pancreatic ductal adenocarcinomas. It has been shown that chemotherapy and radiotherapy do not affect the prognosis. It has been stated that surgical application may be the most appropriate form of treatment, but its benefit has not been demonstrated yet [11,12].
There may be inconsistency between the patient's history, clinical and physical examination findings, and previous clinical diagnoses in patients who applied to the outpatient clinic with previous imaging. In this case, old imaging should be examined, and if necessary, repeated imaging or advanced imaging should be preferred. Technical differences between MRI devices and the experience of radiologists in interpreting MRI can cause diagnostic difficulties. In addition, clinicians and radiologists should evaluate not only bone and muscle tissues but also surrounding tissues when examining musculoskeletal MRIs.
In conclusion, this case presents an unusual presentation of the malignancy with a poor prognosis. More important underlying causes of LBP can be identified with a detailed history, good physical examination, and careful examination of imaging methods.
Author Contribution Each listed author contributed to the design and drafting of this manuscript and approved its last version.
Data Availability Data and materials are available.
Code Availability Not applicable.

Declarations
Ethics Approval Not applicable.

Consent to Participate
The patient's son has given his consent for the participation.

Consent for Publication
The patient's son has given his consent for the publication of this article.

Conflict of Interest
The authors declare no competing interests.