Rand Hindosh, MD1, Hammad Liaquat, MD2, Aumi Brahmbhatt, MD1, Lisa Stoll, MD, MPH3, Yacoub Faroun, MD2, Roderick M. Quiros, MD2, Ayaz Matin, MD2; 1St. Luke's University Health Network, Easton, PA; 2St. Luke's University Health Network, Bethlehem, PA; 3Saint Luke's, Bethlehem, PA
Introduction: Pancreatic cancer is one of the leading causes of cancer related mortality. Skeletal muscle metastases (SMM) of pancreatic cancer are uncommon and associated with poor prognosis. We present a rare case of pancreatic cancer with metastasis to the rectus abdominis muscle.
Methods: A 61 year old Caucasian female initially presented with jaundice, pale stools, dark urine, pruritis and 15 lb weight loss. She had no family history of pancreatic cancer. She drank alcohol rarely and was a smoker at time of diagnosis. Her labs showed T bili 11 (majority conjugated on fractionation), alkaline phosphatase 282, ALT 138, AST 56, and normal albumin, creatinine and CBC. CT scan showed a 2.8 cm mass in the pancreatic head with dilatation of biliary and pancreatic ducts. Serum CA 19-9 level was 1810 U/ml. The mass was confirmed to be pancreatic adenocarcinoma on biopsy taken during endoscopic ultrasound (Image 1). ERCP was performed and a biliary stent was placed to relieve the obstruction. No metastases were seen on further imaging. Molecular tests were negative for deleterious mutations. Subsequent treatment course included neoadjuvant FOLFIRINOX chemotherapy followed by Whipple procedure where lymphovascular and perineural invasion of the cancer with 4/18 positive lymph nodes was noted (Stage III; ypT3, pN2, grade 1). Patient received adjuvant chemoradiation with capecitabine which she finished two months later. Early follow up imaging did not show any recurrence of cancer and CA 19-9 decreased to 46 U/ml. However, eight months later, she developed lower quadrant abdominal pain and CA 19-9 level increased to 1503 U/ml. A PET scan was done which revealed a 4.7 cm mass in the left rectus abdominus muscle confirmed on muscle biopsy to be metastatic pancreatic cancer (Image 2). No pancreatic mass was seen (stage IV;T0, N0, M1 isolated). Chemotherapy was restarted with Nab-paclitaxel and gemcitabine to which the patient has responded so far (decreased size of lesion and CA 19-9 decreased to 135 U/ml). Patient will receive a total of 4 cycles of chemotherapy and then evaluated for surgical resection or radiation. Discussion: To our knowledge, only five cases of abdominal wall metastasis of pancreatic cancer have been reported in the past. Treatment options include chemotherapy, radiation and surgical excision but there is no consensus on management due to rarity of presentation.
Image 1: US right upper quadrant shows a 2.9 cm pancreatic head mass (A) which is confirmed on CT abdomen and pelvis with contrast (Arrow) in the absence of any metastatic lesions (B). H & E stain (20X) of pancreatic tissue from pancreatic EUS biopsy (C) showing adenocarcinoma (arrows) and nuclear pleomorphism (4:1 ratio), incomplete glands and few single cells in a background of desmoplastic stroma. H & E stain (20X) of pancreatic tissue from whipple procedure (D) showing perineural invasion by pancreatic adenocarcinoma. Blue arrow indicates nerve while red arrow indicates adenocarcinoma.
Image 2: PET CT scan showing asymmetric thickening of the left rectus abdominis muscle with a 4.7 cm focally intense FDG activity (arrow) in (A). CT abdomen with contrast shows decreased size of metastases (now measuring 1.6 cm in size) in the persistently thickened left rectus abdominis muscle (arrow) after chemotherapy in (B). H & E stain (20X) from biopsy of rectus abdominis mass seen on PET scan which shows adenocarcinoma involving atrophic skeletal muscle fibers (nuclear bags – blue arrows) in (C). DPC4 immunohistochemistry stain (40X) from skeletal muscle tissue showing loss of expression within the adenocarcinoma, consistent with pancreatic origin while background stromal cells maintain DPC4 expression (D).
Disclosures: Rand Hindosh indicated no relevant financial relationships. Hammad Liaquat indicated no relevant financial relationships. Aumi Brahmbhatt indicated no relevant financial relationships. Lisa Stoll indicated no relevant financial relationships. Yacoub Faroun indicated no relevant financial relationships. Roderick Quiros indicated no relevant financial relationships. Ayaz Matin indicated no relevant financial relationships.