Hypertrophic Osteoarthropathy

Hypertrophic osteoarthropathy (HO), formerly and incorrectly referred to as hypertrophic pulmonary osteoarthropathy, has primary and secondary forms. The primary form (pachydermoperiostosis) is often familial and is more commonly seen in males.

The secondary form can be seen in a variety of pulmonary and hepatic conditions, including:

• Lung cancer
• Mesothelioma
• Carcinomas of liver and gut
• Inflammatory bowel disease
• Liver cirrhosis
• Congenital cyanotic heart disease
• Pulmonary fibrosis
• Empyema
• Graves disease
• Thalassemia

Patients can present with clubbing of fingers, periostosis of distal long bones, thickening of skin over face and ankles, gynecomastia, and arthritis and synovitis. The synovitis is accompanied by a viscous, non-inflammatory effusion.

Various etiologies have been proposed, but the most recent thought is that it is due to arteriovenous shunting (e.g., in the liver, lung, or various tumors). The idea is that unfragmented megakaryocytes get delivered to distal sites in systemic circulation instead of being filtered in the lungs. This leads to production of growth factors (PDGF and VEGF), which lead to angiogenesis, endothelial hyperplasia. In certain lung tumors, there is de novo production of these growth factors by tumor, which makes it to the peripheral circulation.

A neurogenic role has also been proposed. This is supported by the fact that pain and deformity resolve with peripheral vagotomy in both primary and secondary forms, even with the primary tumor intact.

Differential diagnosis for Multifocal Periostitis in Adults and children were covered earlier.

References

Armstrong DJ, et al. Hypertrophic pulmonary osteoarthropathy (HPOA) (Pierre Marie-Bamberger syndrome): two cases presenting as acute inflammatory arthritis. Description and review of the literature. Rheumatol Int. 2007 Feb;27(4):399-402.

Splenic Abscess

The CECT images above are from a patient who underwent sleeve gastrectomy (blue arrow) and experienced worsening abdominal pain in the weeks that followed. She was admitted with sepsis. There are necrotic areas within the spleen and multiple rim enhancing collections of air and fluid (red arrows) compatible with abscesses. Left upper quadrant fluid collections (sterile and infected) are a known complication of bariatric surgery.

REFERENCES

Blachar A and Federle MP. Gastrointestinal complications of Roux-en-Y gastric bypass surgery in patients who are morbidly obese: findings on radiography and CT. AJR Am J Roentgenol 2002;179:1437-42.

Yu J, Turner MA, Cho SR, et al. Normal anatomy and complications after gastric bypass surgery: helical CT findings. Radiology 2004;231:753-60.

Necrotizing Pancreatitis

Necrotizing pancreatitis is perhaps the most severe complication of acute pancreatitis because of the high associated mortality rate.  Bacterial contamination of pancreatic necrosis carries a 40-70% mortality rate, even after surgical debridement. Thus, early detection of necrosis is crucial in patient management. 

CECT will show lack of enhancement of the necrotic regions.  This finding is usually accompanied by other imaging indicators of pancreatitis such as infiltration of the peripancreatic fat planes. T2W MRI will show increased signal intensity of the necrotic regions while T1W post contrast images will show nonenhancing areas with decreased signal intensity. 

The above CECT images are from a young male admitted with acute pancreatitis whose clinical status was worsening. Lack of enhancement of the distal pancreatic body and tail are seen (red arrow)  consistent with necrosis. Note, the normal enhancement of the pancreatic head (blue arrow).

REFERENCES
Balthazar EJ. Acute pancreatitis: assessment of severity with clinical and CT evaluation. Radiology 2002;23:603-13.
O'Connor OJ, Buckley JM, Maher MM. Imaging of the complications of acute pancreatitis. AJR Am J Roentgenol 2011;197:W375-81.

To Stent or Not to Stent?

The above CECT axial images are part of a trauma work up in a young patient involved in an MVA with multiple abdominal injuries. Several liver lacerations are seen with subtle active extravasation of contrast. The third axial image shows a focal dissection at the origin of the celiac artery (red arrow). Sagittal reconstruction demonstrates absence of the celiac origin (the SMA origin is seen). Conventional angiogram shows a dissection at the origin of the celiac artery with opacification of its distal branches.

Typically, this dissection would be treated with a stent requiring short term anti-coagulation therapy (at least 6 months). However, a patient with multiple liver lacerations is not a candidate for anti-coagulation. Thus, despite injury to a major abdominal visceral artery, no intervention could be performed. The patient was monitored for hemodynamic stability and received several units of packed RBCs with no further drop in hematocrit.

Calvarial Metastases

Calvarial metastases tend to have aggressive features on MR imaging including ill defined margins, multiplicity, bony erosion/invasion, and seeding of the meninges. The most common primary malignancies to cause skull metastases are breast, lung, and prostate cancer.

The above T1W pre- and post contrast sagittal images demonstrate a large, lobulated calvarial lesion which enhances with contrast. This was found to be a metastatic focus in a patient with thyroid carcinoma.  


REFERENCES
Nemeth AJ, Henson JW, Mullins ME, et al. Improved detection of skull metastasis with diffusion-weighted MR imaging. AJNR Am J Neuroradiol 2007;28:1088-92.
Nguyen BD, McNaughton D. AJR teaching file: nuclear imaging of a tender skull mass. Am J Roentgenol 2007;189(6):S61-3.

Grade 1 Renal Injury

Axial image from a CECT obtained as part of a trauma work up demonstrates a crescentic collection inseparable from the right kidney, with mass effect on the renal parenchyma, containing regions of high attenuation. The right renal parenchyma enhances homogeneously. Findings are compatible with a subcapsular hematoma which falls under the spectrum of Grade 1 renal injuries, previously discussed here.

REFERENCES
Harris AC, Zwirewich CV, Lyburn ID, et al. CT findings in blunt renal trauma. Radiographics 2001;21:S201-14.

Osteochondritis Dissecans Revisited

Coronal and sagittal T1 and T2WI demonstrate curvilinear low signal intensity in the medial femoral condyle on T1WI with high signal on the corresponding T2WI. Findings are consistent with osteochondritis dissecans previously discussed here.