The Abdominal Wall Lumps and Bumps: Cross-Sectional Imaging Spectrum Vivek Virmani, MD, FRCR, Vineeta Sethi, MD, Najla Fasih, FRCR, John Ryan, FRCPC, Ania Kielar, FRCPC  Canadian Association of Radiologists Journal  Volume 65, Issue 1, Pages 9-18 (February 2014) DOI: 10.1016/j.carj.2012.02.001 Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 1 Abdominal-wall endometriosis in a 24-year-old woman with a history of caesarean section who presented with continuing cyclical pain symptoms. (A) Axial T2W, (B) fat-suppressed TIW, and (C) postcontrast magnetic resonance imaging, revealing a spiculated mass (arrows) in the region of the surgical scar, which is isointense compared with muscle on T2W, mildly hyperintense on T1W, and showing moderate contrast enhancement. A few foci of T1W and T2W hyperintensities (arrowheads) are seen, which represent foci of hemorrhage. Canadian Association of Radiologists Journal 2014 65, 9-18DOI: (10.1016/j.carj.2012.02.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 2 Anterior abdominal-wall desmoid in a 36-year-old woman, 6 months postpartum. (A) Axial T2W and (B) T1W magnetic resonance imaging (MRI), revealing a mass lesion (arrows) in the right rectus, which is hyperintense on T2W and isointense on T1W. Foci of low signal intensity on T2W represent collagen deposition. (B, inset) Contrast-enhanced MRI, revealing intense enhancement. Canadian Association of Radiologists Journal 2014 65, 9-18DOI: (10.1016/j.carj.2012.02.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 3 Left rectus sheath hematoma (black arrow) in a 55-year-old woman on anticoagulants. Hematocrit effect (arrowhead) and active extravasation (white arrow) is seen. Canadian Association of Radiologists Journal 2014 65, 9-18DOI: (10.1016/j.carj.2012.02.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 4 Epidermal inclusion cyst in a 34-year-old asymptomatic man. (A) Axial contrast computed tomography, revealing a well-defined tubular hypodense mass (arrow) in the anterior abdominal wall, with peripheral calcification (arrowhead). (B) Axial T2W magnetic resonance imaging (MRI) and (C) Axial T1W MRI, revealing the lesion (arrows) to be iso- to mildly hyperintense on T2W and isointense on T1W. (C, inset) Contrast-enhanced MRI, which does not show significant enhancement. An epidermoid cyst often does not follow cystic signal intensity on MRI due to heterogeneous internal contents. Canadian Association of Radiologists Journal 2014 65, 9-18DOI: (10.1016/j.carj.2012.02.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 5 A 16-year-old boy with vascular malformation of the abdominal wall. (A) Axial computed tomography, revealing an irregular subcutaneous mass (white arrows) in the left flank, with fibrofatty matrix and phlebolith (arrowhead). Note is made of incidental left renal cyst (black arrow). (B) Postcontrast administration fat-saturated T1W, and (C) fat-saturated T2W magnetic resonance imaging, revealing the subcutaneous mass (dashed arrows) to have fibrofatty matrix with solid tissue (solid arrows), which is isointense on T1W and hyperintense on T2W. Multiple enhancing vessels are also seen (C, arrowhead). Surgical excision revealed this to be a lymphaticovenous malformation. Canadian Association of Radiologists Journal 2014 65, 9-18DOI: (10.1016/j.carj.2012.02.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 6 A 45-year-old woman who presented with right upper quadrant lump and tenderness. Axial contrast computed tomography, demonstrating asymmetric subcutaneous bulk on the right side, with a fat-density lesion with a thin capsule (arrows). (Inset) A speck of calcification (arrowhead) is seen in the inferior part of the lipoma. These lesions may often be difficult to distinguish from the subcutaneous fat. Canadian Association of Radiologists Journal 2014 65, 9-18DOI: (10.1016/j.carj.2012.02.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 7 Extensive subcutaneous and deep neurofibromas in a 33-year-old woman with neurofibromatosis type 1. (A) Axial T2W magnetic resonance imaging (MRI) with fat saturation, revealing multiple subcutaneous (dashed arrows), intramuscular (white arrowhead), retroperitoneal (white arrows), and vertebral canal (black arrowheads) neurofibromas. These are hyperintense on T2W. The target sign is well seen in many of these (dashed arrows). (B) Contrast-enhanced fat-saturated T1W MRI of the pelvis, revealing enhancing neurofibromas along the course of the sciatic nerve (white arrows); a dominant mass (arrowhead) is seen in the left inguinal region, which is predominantly cystic and shows enhancement of the thick septa. This was proven on pathology to be neurofibrosarcoma. Canadian Association of Radiologists Journal 2014 65, 9-18DOI: (10.1016/j.carj.2012.02.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 8 Subcutaneous leiomyoma in a 28-year-old man with human immunodeficiency virus. Axial computed tomography, revealing an enhancing subcutaneous mass (arrow) in the anterior pelvic wall. (Inset) Doppler ultrasonography, demonstrating the hypoechoic lobulated mass (arrow) with moderate vascularity. The core biopsy of the lesion revealed it to be subcutaneous leiomyoma. This figure is available in colour online at http://carjonline.org/. Canadian Association of Radiologists Journal 2014 65, 9-18DOI: (10.1016/j.carj.2012.02.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 9 A 32-year-old woman with pain and swelling in the right flank. Axial contrast computed tomography, revealing a homogenous avidly enhancing lesion (arrow) in the lateral muscles of the right abdominal wall. Hemangiopericytoma was confirmed on surgical excision. Canadian Association of Radiologists Journal 2014 65, 9-18DOI: (10.1016/j.carj.2012.02.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 10 A 37-year-old man with a painless slow-growing mass in the umbilical region. Axial contrast computed tomography, revealing a nodular heterogeneously enhancing mass (arrow) arising from the skin and extending into the subcutaneous tissues. It was treated by wide surgical excision, and histology confirmed dermatofibrosarcoma protuberans with a few foci of fibrosarcoma within it. Canadian Association of Radiologists Journal 2014 65, 9-18DOI: (10.1016/j.carj.2012.02.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 11 A 65-year-old man with colon cancer (mucinous adenocarcinoma) resection 2 years earlier presented with abdominal-wall recurrences. Axial contrast computed tomography of the pelvis, revealing a large heterogeneously enhancing metastatic deposit (arrow) in the anterior pelvic wall, with faint calcifications (arrowhead) within it. (Inset) Right anterior abdominal-wall metastatic deposit (white arrow) and peritoneal carcinomatosis (black arrow). Canadian Association of Radiologists Journal 2014 65, 9-18DOI: (10.1016/j.carj.2012.02.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 12 Tumour seeding in a 63-year-old man with hepatocellular carcinoma. Axial contrast computed tomography section performed 8 months after radiofrequency ablation, revealing an enhancing nodule (arrow) in the right anterior abdominal wall along the course of the inserted electrode, which signified needle-tract seeding. (Inset) A nonenhancing nodule in segment VI of liver (arrow), which signified a successfully ablated lesion. Canadian Association of Radiologists Journal 2014 65, 9-18DOI: (10.1016/j.carj.2012.02.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 13 A 25-year-old man with diffuse systemic lymphoma and involvement of the abdominal wall. Axial computed tomography, revealing a large mesenteric mass lesion (black arrow) that encased the vessels, characteristic for lymphoma. A noncontiguous lymphomatous deposit (white arrow) is also seen in the left rectus muscle. Canadian Association of Radiologists Journal 2014 65, 9-18DOI: (10.1016/j.carj.2012.02.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 14 A 42-year-old woman with subcutaneous myxoid liposarcoma. T1W magnetic resonance imaging (MRI), revealing a lobulated low signal intensity subcutaneous mass (arrow) in the posterior abdominal wall, with foci of high intensity (arrowhead). (Inset) Fat-suppressed contrast-enhanced MRI reveals intense enhancement (arrow). Canadian Association of Radiologists Journal 2014 65, 9-18DOI: (10.1016/j.carj.2012.02.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 15 A 64-year-old man with a chondrosarcoma arising from the 12th rib. Axial contrast computed tomography, revealing a heterogeneous mass (arrow) arising from the rib, with both a retroperitoneal component and external soft tissue in the posterolateral abdominal wall. Chondroid matrix is seen, which is characteristic of this tumour. Canadian Association of Radiologists Journal 2014 65, 9-18DOI: (10.1016/j.carj.2012.02.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 16 Right rectus muscle abscess (arrow) in a 25-year-old man after surgery for appendectomy. Canadian Association of Radiologists Journal 2014 65, 9-18DOI: (10.1016/j.carj.2012.02.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 17 Fat-saturated contrast-enhanced T1W magnetic resonance imaging, revealing a ring enhancing lesion (arrow) in the left rectus muscle, which was surgically proven to be a primary tubercular abscess. Canadian Association of Radiologists Journal 2014 65, 9-18DOI: (10.1016/j.carj.2012.02.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 18 Necrotizing fasciitis in a 59-year-old man with diabetes mellitus. Axial computed tomography, revealing gas dissecting along the superficial fascial planes (arrows). Canadian Association of Radiologists Journal 2014 65, 9-18DOI: (10.1016/j.carj.2012.02.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 19 A 14-year-old patient with subcutaneous and intramuscular cysticercosis. Axial computed tomography, revealing multiple calcified lesions in the subcutaneous tissues (dashed arrows), in the gluteal muscles (solid arrows), and in the retroperitoneum (arrowheads). The patient also had central nervous system involvement, with multiple ring and disk enhancing lesions in the brain (not shown). Canadian Association of Radiologists Journal 2014 65, 9-18DOI: (10.1016/j.carj.2012.02.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 20 A 38-year-old woman with ovarian carcinoma and periumbilical nodule. Axial computed tomography, revealing a complex ovarian mass (black arrow) with a calcified periumbilical nodule (white arrow). A possible diagnosis of metastases was considered, but excisional biopsy revealed it to be stitch granuloma from a remote appendectomy. Canadian Association of Radiologists Journal 2014 65, 9-18DOI: (10.1016/j.carj.2012.02.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 21 Gallstone spillage in a 55-year-old woman, with a history of laparoscopic cholecystectomy 4 months earlier, who presented with right upper quadrant pain. Axial contrast computed tomography, revealing a gallstone (arrow) at the trocar site in the abdominal wall, with adjacent inflammation. Canadian Association of Radiologists Journal 2014 65, 9-18DOI: (10.1016/j.carj.2012.02.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

Figure 22 A 25-year-old man with a history of severe motor vehicle accident and head injury. A computed tomography of the abdomen, revealing a bone flap (arrow) within the left anterior abdominal wall. (Inset) Three-phase technetium bone scan done 6 weeks after the craniectomy, showing a viable bone flap in the left iliac fossa (circled). Canadian Association of Radiologists Journal 2014 65, 9-18DOI: (10.1016/j.carj.2012.02.001) Copyright © 2014 Canadian Association of Radiologists Terms and Conditions