We Report a Rare Case of Pancreatic Adenocarcinoma Presenting as Panniculitis

Abstract

Purpose: Case: A 63 year old female with a known deleterious mutation in the BRCA2 gene presents with bilateral lower extremity nodules. The nodules were erythematous, edematous, ulcerated, non-confluent and painful to touch. A left leg punch biopsy was performed and the pathology was consistent with subcutaneous fat necrosis. Due to the association of both fat necrosis and BRCA2 gene mutations with pancreatic pathology a computed tomography (CT) of the abdomen was performed. The CT showed a mass in the tail of the pancreas with associated mesenteric lymphadenopathy and multiple liver metastases. An endoscopic ultrasound was performed and showed a 9.8 cm by 7 cm heterogeneous tail mass. Fine needle aspiration was performed with a 25 gauge needle. The on-site pathologist confirmed a well differentiated adenocarcinoma. The patient ultimately opted for hospice care given her poor functional status. Discussion: Pancreatic panniculitis, also known as subcutaneous fat necrosis, is a rare manifestation of pancreatic disease with a reported incidence ranging from 0.3 to 3%. The pathogenesis is unknown but likely related to the release of pancreatic enzymes into the systemic circulation resulting in autodigestion of tissue. Immunologic processes have also been implicated. The proposed mechanism described in one patient presenting with pancreatic panniculitis was deposition of immune complexes in the microcirculation resulting in clinically apparent nodules. Similar to our case, patients typically present with exquisitely tender, edematous, erythematous nodules on the distal aspects of the lower extremities. Ulceration may occur leading to drainage of an oily, brown, viscous fluid consisting of necrotic subcutaneous fat. Nodules can spread to any part of the body and joints can also be involved. Histologically pancreatic panniculitis is characterized by lobular fat necrosis without any vasculitis. The adipocytes are annucleated with a thick, shadowing wall. These are called “ghost cells”. Pancreatitis is the most common underlying pancreatic disorder associated with pancreatic panniculitis. Neoplasms have also been implicated with acinar cell carcinoma being the most common. Other tumor types such as ductal adenocarcinoma and neuro-endocrine have also been implicated. The differential diagnosis of these painful nodules includes erythema nodosum, erythema induratum, alpha-1 antitrypsin deficiency panniculitis, infectious panniculitis or subcutaneous metastases. Unfortunately, treatment is supportive and directed towards the underlying pancreatic disorder.