Prominent Calcaneal Trabeculation

A prominent calcaneal trabeculation can appear as a sclerotic line along the inferior aspect of the calcaneus on the lateral view. It is a common normal variant that may simulate a stress fracture.

References

Keats TE and Anderson MW. Atlas of Normal Roentgen Variants That May Simulate Disease. 8th edition, page 886; Mosby (2004).

Subperiosteal Orbital Hemorrhage

Subperiosteal orbital hemorrhage is an uncommon condition that may be caused by direct trauma or various behaviors that result in increased venous pressure, such as the Valsalva maneuver. Its name describes the pathology and suggests the imaging findings.

CT and MRI will show a well-defined blood collection in the orbit, usually superiorly, that displaces the conal fat and extra-ocular muscles. Differential considerations include metastasis, lymphoma, or orbital pseudotumor.

References

Crawford SD, Patel MR. Bilateral supraorbital masses after prolonged headlock injury: an unusual manifestation of orbital subperiosteal hematomas. AJR Am J Roentgenol. 2005 Mar;184(3 Suppl):S2-3.

Endocardial Fibroelastosis

Endocardial fibroelastosis is a rare condition that results in diffuse thickening of the ventricular endocardium and presents as unexplained heart failure in infants and children.

It can be divided into primary and secondary forms. Primary endocardial fibroelastosis is not associated with any significant structural cardiac abnormality, while secondary endocardial fibroelastosis is associated with congenital cardiac abnormalities, most commonly hypoplastic left heart syndrome and aortic stenosis.

Echocardiography may show echogenic endocardial surface and a spherical shape to the left ventricle, but this appearance has a weak correlation with endocardial fibroelastosis on histology. Perfusion MRI shows a hypointense layer at the endocardial surface that corresponds to an area of delayed enhancement.

References

• Stranzinger E, Ensing GJ, Hernandez RJ. MR findings of endocardial fibroelastosis in children. Pediatr Radiol. 2008 Mar;38(3):292-6.
• Tworetzky W, del Nido PJ, Powell AJ, Marshall AC, Lock JE, Geva T. Usefulness of magnetic resonance imaging of left ventricular endocardial fibroelastosis in infants after fetal intervention for aortic valve stenosis. Am J Cardiol. 2005 Dec 1;96(11):1568-70.

Mesenteric Calcifications

• Calcified lymph nodes: Treated lymphoma, infection (tuberculosis, fungal), sarcoidosis
• Pancreatic saponification:
• Mucinous metastases: From ovarian or gastrointestinal neoplasms
• Carcinoid tumor: Single mass with significant desmoplastic reaction causing tethering of adjacent loops of small bowel toward the mass
• Calcified metastatic implants: Ovarian carcinoma, mucinous colon carcinoma, or gastric carcinoma.
• Chronic sclerosing mesenteritis:
• Peritoneal echinococcosis:

References

• Macari M, Balthazar EJ. CT of bowel wall thickening: significance and pitfalls of interpretation. AJR Am J Roentgenol. 2001 May;176(5):1105-16.
• Pickhardt PJ, Bhalla S. Unusual nonneoplastic peritoneal and subperitoneal conditions: CT findings. Radiographics. 2005 May-Jun;25(3):719-30.
• Sheth S, Horton KM, Garland MR, Fishman EK. Mesenteric neoplasms: CT appearances of primary and secondary tumors and differential diagnosis. Radiographics. 2003 Mar-Apr;23(2):457-73.

Congenital Pulmonary Airway Malformation

Congenital pulmonary airway malformation (CPAM), formerly congenital cystic adenomatoid malformation (CCAM), is the most commonly diagnosed prenatal lung malformation. There is abnormal branching of the immature bronchioles and abnormal alveolar development. The immature airways usually communicate with the normal tracheobronchial tree, resulting in both cystic and solid areas.

The expanded classification of CPAM includes the original types 1, 2, and 3, and two new types: 0 and 4.

• Type 0: Represents an abnormality of the trachea and mainstem bronchi. Incompatible with life.
• Type 1: Represents an abnormality of the bronchial/proximal bronchiolar region. The most common type (60%). Single or multiple large cysts (2–10 cm in diameter) surrounded by smaller cysts and a compressed normal parenchyma. CT shows one or more large, air-filled cysts with or without gas-fluid levels. MR shows T2-hyperintense uni- or multilocular lesions with discrete walls.
• Type 2: Represents an abnormality of the bronchiolar region. Small cysts (0.5 cm - 2 cm). Second most common type (20%). Frequently associated with other congenital anomalies. CT may show a gas-filled multicystic mass or a focal area of consolidation (our case). The MR appearance depends on the composition of the malformation and is variable.
• Type 3: Represents an abnormality of the terminal bronchiolar/alveolar duct region. Third most common type (10%). Tiny cysts (< 0.2 cm in diameter). Frequently associated with other congenital anomalies. Associated with maternal polyhydramnios in ~80% of cases. Can involve an entire lobe or the whole lung. The tiny cysts are too small to resolve by CT; therefore, the lesion appears as a solid mass. MR shows a homogeneously T2-hyperintense solid mass with normal adjacent parenchyma.
• Type 4: Represents an abnormality of the distal acinus or alveolar saccular/alveolus region. May or may not be the same thing as pleuropulmonary blastoma. Presents before 4 years of age. Sudden respiratory distress due to tension pneumothorax is a unique feature of this subtype. Imaging reveals a large lesion, usually localized to one lobe, with large air-filled cysts. Mediastinal shift may be out of proportion to the mild/absent symptoms.

It is important to remember that CPAM and sequestration can coexist and manifest as a mixed lesion, so a search for systemic arterial supply is helpful. Internal gas-fluid levels may be seen in any of the subtypes if there is superimposed infection.

The images shown here are from a neonate with a lung mass identified at prenatal ultrasound. The radiograph shows an oval lesion in the left lung base medially, which was confirmed by CT. Biopsy showed a type 2 CPAM.

References

• Daltro P, Werner H, Gasparetto TD, Domingues RC, Rodrigues L, Marchiori E, Gasparetto EL. Congenital chest malformations: a multimodality approach with emphasis on fetal MR imaging. Radiographics. 2010 Mar-Apr;30(2):385-95.
• Kim WS, Lee KS, Kim IO, Suh YL, Im JG, Yeon KM, Chi JG, Han BK, Han MC. Congenital cystic adenomatoid malformation of the lung: CT-pathologic correlation. AJR Am J Roentgenol. 1997 Jan;168(1):47-53.
• Lee EY, Boiselle PM, Cleveland RH. Multidetector CT evaluation of congenital lung anomalies. Radiology. 2008 Jun;247(3):632-48.
• Stocker JT. Congenital pulmonary airway malformation: a new name and an expanded classification of congenital cystic adenomatoid malformations of the lung. Histopathology 2002;41(suppl 2): 424–31.

Splenic Abscess after Infarction

Emboli (septic or sterile) are the most common cause of splenic infarctions, followed by local thrombosis (e.g., myelofibrosis, sickle cell disease, leukemia, and lymphoma), vasculitiides, pancreatic disease, splenic artery aneurysm, and splenic torsion.

In the acute phase, splenic infarctions are characterized peripheral low-attenuation lesions that may be wedge-shaped (classic), round or irregular (more common). In some cases, they may present as heterogeneous and poorly marginated lesions that are similar to abscesses and tumors. Later on, there is progressive volume loss and possibly calcification with hypertrophy of the surrounding normal spleen. Liquefaction and necrosis may also occur, with the risk of outward expansion, subcapsular hemorrhage, peritoneal hemorrhage.

Splenic infarctions may be complicated by abscess. The presence of gas in an intrasplenic collection suggests an abscess, but the majority of splenic abscesses do not contain gas. When gas is seen in an infarcted spleen, however, the issue is a bit more complicated. This is because gas in an organ following infarction does not always point to an infectious etiology. Gas formation has been reported in the kidney, liver, and spleen after transcatheter embolization, and is thought to be due to liberation of oxygen from oxyhemoglobin.

Therefore, it is important to differentiate gas in an abscess from gas following infarction. Multiple small gas bubbles throughout the organ, with most of the gas in the more central portions suggests a nonsuppurative origin.

References

• Levy JM, Wasserman PI, Weiland DE. Nonsuppurative gas formation in the spleen after transcatheter splenic infarction. Radiology. 1981 May;139(2):375-6.
• Rabushka LS, Kawashima A, Fishman EK. Imaging of the spleen: CT with supplemental MR examination. Radiographics. 1994 Mar;14(2):307-32.

Polypoid Lesions of the Small Bowel

Polypoid lesions of the small bowel can be mucosal or submucosal, which are differentiated by the angle they form with the small bowel wall. Mucosal lesions tend to form acute angles, while submucosal lesions form right or slightly obtuse angles. This distinction gets hard with small (< 2cm) lesions, however.

Almost 50% of submucosal lesions undergo necrosis and cavitation, giving us a submucosal "bull's-eye" or "target" appearance.

Muscosal lesions

• Polyps: May be pedunculated or sessile. Most commonly adenomas or hamartomas. When multiple, consider familial adenomatous polyposis syndrome (small bowel involved in 95% of patients) or Peutz-Jeghers syndrome (hamartomas). Coexistence of multiple duodenal polyps should steer you towards familial adenomatous polyposis syndrome, while a few large polyps in the distal duodenum and jejunum should steer you towards Peutz-Jeghers syndrome. Obviously if you could look at the patient and saw pigmented skin and mucosal lesions, you'd go with Peutz-Jeghers.
• Carcinoid: Can appear as mucosal lesions as one or more small sessile polyps in the distal ileum. By far the most common neoplasm in the distal small bowel.
• Adenocarcinomas: Usually in the duodenum, at or distal to the papilla of Vater, or in the proximal jejunum within 30 cm of the ligament of Treitz. Can ulcerate.

Submucosal Lesions

• Multiple submucosal masses: Think of hematogenous metastases (melanoma, breast or lung), lymphoma, multiple carcinoid tumors (will be mostly in the ileum), multiple neurofibromas (rarely ulcerate), and Kaposi sarcoma
• Solitary submucosal mass: Think benign lesions like lipoma, gastrointestinal stromal tumor, hemangioma, or neurofibroma.
• Pedunculated lesions: Large pedunculated lesions in the ileum are most commonly lipomas, inflammatory fibroid polyps, and inverted Meckel diverticula.

References

Levine MS, Rubesin SE, Laufer I. Pattern approach for diseases of mesenteric small bowel on barium studies. Radiology. 2008 Nov;249(2):445-60.