Amar Udare, MBBS, MD

A 45-year-old male patient presented with pain in the right iliac fossa.


Contrast axial CT scan at the level of the lower abdomen shows a fat-density ovoid structure adjacent to ascending colon, with a thin high-density rim, surrounding inflammatory fat stranding, with a central hyperdensity (black arrow in Figure 2).


Acute epiploic appendagitis is a self-limited inflammation of the appendices epiploicae. Epiploic appendages are peritoneal pouches arising from the serosal surface of the colon and are attached by a vascular stalk. The largest ones are located near the sigmoid colon and hence rectosigmoid junction is the most common site for acute epiploic appendagitis.

• Presents as acute right iliac fossa pain

• Torsion of epiploic appendages, with resultant ischemia has been implicated as the cause of acute epiploic appendagitis

• Prior to advent of CT, most cases were diagnosed at surgery 

• Oval non-compressible hyperechoic mass at the site of maximum tenderness, adjacent to the colon, with no central blood flow on color Doppler US images.

• Oval lesion less than 5 cm in diameter with fatty attenuation abutting the anterior colonic wall with surrounding inflammatory changes

• Central area of high attenuation due to venous thrombosis can be seen.

: Solitary large nonenhancing omental mass with heterogeneous attenuation, which lacks the hyperattenuating ring that is seen in epiploic appendagitis

 Colonic diverticula with inflammation or abscess in the mesocolon and with adjacent colonic wall thickening

Well-defined soft-tissue mass containing areas of fat attenuation to an ill-defined area of higher attenuation in the root of the small-bowel mesentery


Treated conservatively with oral anti-inflammatory medication, and antibiotics are not routinely indicated.


1. Singh A, Gervais D, Hahn P, Sagar P, Mueller P, Novelline R. Acute Epiploic Appendagitis and Its Mimics. 

2. Gaillard F. Epiploic appendagitis. Radiopaedia.org. 2016 [cited 15 December 2016]. Available from: https://radiopaedia.org/articles/epiploic-appendagitis.

Poll

Image IQ: 45 y/o, Pain in Right Iliac Fossa

A 50-year-old diabetic patient presented with fever, dysuria and abdominal pain.


Axial and coronal CT of the abdomen shows gross enlargement and destruction of left renal parenchyma with bubbly areas of gas collection within the parenchyma.

Emphysematous pyelonephritis is a life-threatening necrotizing infection characterized by gas formation within or surrounding the kidneys.

 Rapidly progressive with high morbidity and mortality.

 Poorly controlled diabetes and immunocompromised status are predisposing conditions.

Mottled gas within the renal fossa or crescentic collections of gas within the Gerota fascia

 Enlarged kidney with nondependent echoes in the renal parenchyma or collecting system

 Kidney may be completely obscured by large amount of perinehric gas

 The distal shadowing have “comet tail” reverberations and low-level echoes that are termed as “dirty shadowing.” Distinguishing them from calculi.

 However, US examination may be affected by the patient’s obesity or bowel meteorism. Additionally bowel gases and calculi are confounding factors. 

• Mottled areas of low attenuation extending radially along the pyramids with parenchymal enlargement and destruction.

• Fluid collections and gas-fluid levels

Type I: Streaky or mottled gas in interstitium of renal parenchyma radiating from medulla to cortex. No fluid collections.

Type 2: Bubbly and/or loculated intrarenal gas with renal and/or perirenal fluid collection.

• Type I is associated with worse prognosis.

Aggressive medical treatment along with percutaneous drainage and partial or complete nephrectomy.

1. Craig W, Wagner B, Travis M. Pyelonephritis: Radiologic-Pathologic Review. 

2. Woodward S, Elsayes K, Akhtar A. Imaging of Emphysematous Pyelonephritis: Self-Assessment Module. 

50-year-old diabetic patient presented with fever, dysuria, and abdominal pain.

Image IQ: 50-year-old Diabetic with Fever, Dysuria, Abdominal Pain

This 45-year-old male patient presents with right upper quadrant pain.

â Angiomyolipoma (AML) is the most common benign solid renal neoplasm observed in clinical practice

.
â Prevalence ranges from 0.2 to 0.6%, females being affected more than males

.
â 80% are sporadic while 20% are associated with tuberous sclerosis complex

.
â As the name suggests, the tumor consists of varying amounts of three elements

â Hyperechoic due to fat component.
â Fat-poor AML can be difficult to diagnose on ultrasound and differentiation from a renal cell carcinoma (RCC) can also be challenging in these cases

.
â Up to 1/3rd cases of AML can show acoustic shadowing which is not seen with RCC

Fat in lesions can be seen as hypodense areas with average HU values less than -10 HU. The presence of fat is however nonspecific and fat has been reported in RCCs as well

.  In such cases, other associated features like larger size, necrosis, invasive/irregular margins, renal vein/ IVC involvement and metastases can help aid diagnosis

Fat-poor AMLs appear as homogeneously hyperdense on unenhanced CT.

Calcification is unusual and should raise the possibility of an alternative diagnosis like RCC

Intra-tumoral hemorrhage can be also seen, especially in tumors larger than 4cm

Larger lesions can have dilated tortuous vessels and aneurysms, which makes them susceptible to intra-tumoral hemorrhage

. A small aneurysm is seen in the lesion depicted in Figure 1.

Fat-poor AMLs show homogenous persistent and gradual enhancement

MRI
â Fat-rich AMLs appear hyperintense on T1 and T2-weighted images owing to their lipid content. Fat suppressed images and in/out phase imaging, aids confirmation of fat.
â Fat-poor AMLs appear as hypointense lesions on T2-weighted images, while fat-invisible AMLs are isointense as the signal is mainly from the muscle component of the lesion

Management:
â Classic angiomyolipoma

Lesions more than 4 cm and with intratumoral aneurysms measuring more than 5mm are at increased risk of spontaneously bleeding, and may need active management.

â Fat-poor AMLs and fat-invisible AMLs may need biopsy for confirmation as these can be difficult to differentiate from RCCs

.
â AMLs associated with tuberous sclerosis complex have increased risk of spontaneous bleeding

 and are more likely to need active management.
â Treatment options include

mTOR inhibitor sirolimus has been useful in a few subtypes.

References
1. Jinzaki M, Silverman S, Akita H, Nagashima Y, Mikami S, Oya M. Renal angiomyolipoma: a radiological classification and update on recent developments in diagnosis and management. Abdominal Imaging. 2014;39(3):588-604.
2. Vos N, Oyen R. Renal Angiomyolipoma: The Good, the Bad, and the Ugly. Journal of the Belgian Society of Radiology. 2018;102(1).
3. Park B. Renal Angiomyolipoma: Radiologic Classification and Imaging Features According to the Amount of Fat. American Journal of Roentgenology. 2017;209(4):826-835.

Can you properly diagnose this 45-year-old patient?

Image IQ: 45-Year-Old Male Patient Presenting with Right Upper Quadrant Pain

16-year-old presenting with swelling beneath the tongue and discomfort.

CT scan of the neck shows a fluid density well defined thin-walled lesion at the floor of the mouth in the sublingual and submandibular space.

Benign retention cysts of the salivary glands seen at the floor of mouth

“Rana” stands for frog in Latin as it often resembles frog’s underside on clinical examination 

Most common site is the floor of mouth involving the sublingual gland and rarely the submandibular gland. Following morphologies have been described:

 Extends into the submandibular space either along the posterior edge of myolohyoid muscle or through a deficiency in the muscle 

These appear as thin walled anechoic lesions at the floor of the mouth.

Well defined unilocular water density (0-10HU) lesion at the floor of the mouth with smooth capsules and devoid of internal septations 

. On MRI owing to the fluid nature of the contents these appear as high signal intensity on T2W and iso/hypointensity on T1W images

Plunging ranulas are seen extending into the submandibular space and the communication between the sublingual and submandibular components can have an appearance of a “tail sign” with smooth tapering anteriorly into the sublingual space 

Infected cysts / recurrent cysts can have thick walls with heterogeneous contents

Surgical resection is the treatment of choice.

References:
1. Gaillard, F. (2018). Ranula | Radiology Reference Article | Radiopaedia.org. [online] Radiopaedia.org. Available at: https://radiopaedia.org/articles/ranula [Accessed 12 Aug. 2018].
2. Kalra V, Mirza K, Malhotra A. Plunging Ranula. Journal of Radiology Case Reports. 2011;5(6):18-24. doi:10.3941/jrcr.v5i6.682.

Can you properly diagnose this 16-year-old?

Image IQ: 16-Year-Old Presenting with Swelling Beneath the Tongue and Discomfort

45-year-old presenting with gradual abdominal swelling.

Scanogram of the abdomen shows diffuse abdominal swelling with displacement of bowel loops displaced laterally. CT of the abdomen shows an ill-defined low density fat containing lesion occupying the entire abdomen and extending into the pelvis. Bowel loops are displaced and compressed anteriorly.

Second most common type of soft tissue sarcoma, representing 10-25% of all soft tissue sarcomas 

Patients usually present in their fifth decade with abdominal swelling and pain

Size is usually more than 5 cm at presentation

Histological types as per WHO (2002 guidelines

.:
o Well-differentiated and dedifferentiated liposarcoma (WDLPS / DDLPS)
o Myxoid and round cell liposarcoma (MLS and RCL)
o Pleomorphic liposarcoma (PLS)

Large lesions may appear as soft tissue masses.

Fat can be seen in lesions in extremity however it is difficult to appreciate in retroperitoneal lesions

Heterogeneous, multi-lobulated well-defined mass.

Identification of fat as echogenic foci can often be difficult and is nonspecific.

Large heterogeneous fat containing lesions with non-lipomatous components. Fat appears as low attenuation on CT (-100HU) and hyperintense on T1W images.

Multiple septae and enhancing soft tissue components are often identified.

Imaging appearance can often point to the subtype

• Well-differentiated and dedifferentiated liposarcoma:

Thick septa (>2mm) and enhancing nodular soft tissue nodules (<1cm) can be present. 

Have high water content can often be mistaken as cystic lesions.

Appear low signal intensity on T1 and high signal on T2.

Diffuse post contrast enhancement distinguishes these from truly cystic lesions.

Round cell subtype has a non-specific appearance on image.

Aggressive lesions with little or no fat.

Well circumscribed enhancing soft tissue lesions.


Surgical resection is the treatment of choice. 

References:
1. Matthyssens L, Creytens D, Ceelen W. Retroperitoneal Liposarcoma: Current Insights in Diagnosis and Treatment. Frontiers in Surgery. 2015;2.
2. O'Regan K, Jagannathan J, Krajewski K, Zukotynski K, Souza F, Wagner A et al. Imaging of Liposarcoma: Classification, Patterns of Tumor Recurrence, and Response to Treatment. American Journal of Roentgenology. 2011;197(1):W37-W43.
3. Murphey M, Arcara L, Fanburg-Smith J. Imaging of Musculoskeletal Liposarcoma with Radiologic-Pathologic Correlation. RadioGraphics. 2005;25(5):1371-1395.

Can you properly diagnose this 45-year old?

Image IQ: 45-year old presenting with gradual abdominal swelling

A 13-year-old female presents with painful swelling in the left temporal region.


Gray scale USG (Figure 1) shows a well-defined anechoic cyst in the left temporalis muscle with an eccentric nodule in the periphery. On color Doppler (Figure 2) there is no internal vascularity in the nodule or the lesion.

• Parasitic tissue infection caused by ingestion of tapeworm eggs (

 Most commonly affects the nervous system.

 Most common infection of the soft tissue, the most common location being the skeletal muscle.

 Endemic in developing countries, however it is now seen in developed countries as well.

 Human beings become occasional hosts of 

 larvae, either via drinking contaminated water or by eating uncooked/undercooked vegetables or pork.

 Cysticerci appear as oblong calcific specks in the skeletal muscles parallel to the muscle fibers, giving a characteristic rice grain appearance.

 High-frequency USG is a relatively inexpensive and readily available and reliable tool.

• Most common USG appearance of soft tissue cysticercosis is that of an intramuscular abscess with an eccentrical cyst having a scolex within.

• Can be associated with mild edema without abscess

• Least common appearance is that of an irregular cyst with no scolex within but with minimal fluid surrounding the cyst on one side indicating leakage of fluid.

Seen as a cystic lesion that is oriented in the direction of the muscle fibers with a hypointense speck suggestive of scolex

• Surgical excision for isolated skeletal muscle or soft tissue cysticercosis associated with abscess.

 Cysts that are not associated with abscess can be treated with anti-helminthic.

 Follow-up USG is done after three weeks of anti-helminthic medication to look for resolution.

1. Naik D, Srinath M, Kumar A. Soft tissue cysticercosis - Ultrasonographic spectrum of the disease. 

2. Firke V. Cysticercosis. Radiopaedia.org [Internet]. Radiopaedia.org. 2016 [cited 15 December 2016]. Available from: https://radiopaedia.org/articles/cysticercosis.

Image IQ: 13 y/o, Painful Swelling in Temporal Region

A 75-year-old male presented with left-sided weakness, headache, and altered sensorium for the past 20 days. Plain and contrast CT scans and MRI brain was obtained.

CT shows a well-defined ring enhancing lesion in the right parietal lobe with perilesional edema out of proportion to the size of the lesion (Figure 1). The ring enhancement is irregular. MR shows that the lesion does not show restriction in its central portion and shows significant perilesional edema on T2W images and irregular rim enhancement on postcontrast images (Figure 2). The provisional diagnosis was that of metastasis and the chest radiograph was reviewed. Based on that, a CT chest was performed which showed a well-defined mass in the left lung (Figure 3), confirming the diagnosis of metastasis.

The differential for ring enhancing lesions can be remembered by the mnemonic MAGIC Lady Doctor:

Metastasis, Abscess, Glioma, Infarct, Contusion,

Metastases are a common cause of a space occupying lesion in the cerebrum. The common primary lesions include 

. Most common site is the cerebral hemisphere followed by the posterior fossa (where they are the most common tumor in adults).

On imaging, metastases are usually multiple and well defined. They cause significant perilesional edema which is usually out of proportion to the tumor. They can present with variable enhancement, which may be solid, punctate, or peripheral ring enhancement. Hemorrhage is commonly associated with melanoma, renal cell carcinoma, choriocarcinoma, thyroid cancer, and lung and breast cancers. Calcification is seen with mucin producing primary carcinomas (gastrointestinal tract) and breast carcinoma. CT is the initial modality of choice while MR is better for further characterization. On spectroscopy, they show absent/decreased NAA and raised choline peak in the lesion without any elevation of choline in the peritumoral region.

1. Gaillard F. Cerebral ring enhancing lesions. Radiopaedia.org. Accessed June 7, 2015. Available from: http://radiopaedia.org/articles/cerebral-ring-enhancing-lesions.

2. Orton T. Cerebral metastases. Radiopaedia.org. Accessed June 7, 2015. Available from: http://radiopaedia.org/articles/cerebral-metastases.

75-year-old male presented with left-sided weakness, headache, and altered sensorium.

Image IQ: 75 y/o Male, Left-sided Weakness, Headache

28-year-old male presented with sensorineural hearing loss for two months. Plain and contrast CT scans with coronal reconstruction have been provided.

Figure 1A–C. Plain CT sections at the level of the posterior fossa.

Figure 2A–C. Post-contrast axial CT sections at the level of the posterior fossa.

Figure 3A–C. Post-contrast coronal CT sections at the level of the posterior fossa.

Figure 4. Coronal reconstruction with bone window.

Diagnosis: Vestibular Schwannoma (acoustic neuroma)


Plain CT shows a relatively ill-defined extra-axial lesion in the right CP angle cistern displacing the cerebellar hemisphere and the vermis to the opposite side (Figure 1). On post-contrast sequences, the lesion appears heterogeneous with mild post-contrast enhancement with nonenhancing areas, suggestive of necrosis/cystic change (Figure 2, 3). There is widening of the internal acoustic meatus (ice-cream cone appearance) (Figure 4).

The top differentials of a CP angle tumor include vestibular schwannoma, meningioma, and epidermoid cyst. A meningioma would show a more homogenous post-contrast enhancement and a dural tail. An epidermoid will show CSF–like density and will show restriction on diffusion. In patients with a known malignancy, metastasis is a possible diagnosis, but usually they have significant perilesional edema and do not cause widening of the internal acoustic meatus.


Vestibular schwannomas are the most common cerebellopontine angle mass lesion (80% of CP angle tumors). They are usually unilateral, and bilateral vestibular schwannomas are seen in neurofibromatosis type 2 (NF2). These are low-grade tumors (WHO grade I) arising from the intracanalicular segment of the vestibular portion of the vestibulocochlear nerve (CN VIII), inferior division being commonly involved than the superior. Histopathologically two types of cells are identified - Antoni type A cells forming the cellular component of the tumor while type B cells contribute to the less cellular, cystic, and myxoid component.

• Widening of the porus acousticus due to the intracalicular component and extra-canalicular extension into the cerebellopontine angle give rise to the trumpeted internal acoustic meatus and ice cream appearance, respectively.

CSF cleft may be present due to their extra axial location.

Hemorrhage and cystic areas may be seen, calcification is not a typical feature.

On post-contrast scans, there is mild to moderate enhancement with nonenhancing cystic/necrotic areas.

Compact Antoni Type cells seen in smaller tumors and are responsible for the low T2 signal relative to CSF.

As schwannomas enlarge, regions of internal necrosis/cyst formation may result in a heterogeneous appearance. There are of higher signal intensity than CSF presumably because of the presence of hemorrage byproducts, necrotic material, or colloid-rich fluid with predominance of Antoni Type B cells.

In addition to intratumoral cysts, extramural (arachnoid) cysts are also associated 7%–10%) with large lesions presumably secondary to elevation and deformation of the leptomeninges.

Post-contrast enhancement is heterogeneous.
 

1. Gaillard F. Acoustic schwannoma. Radiopaedia.org. Available from: http://radiopaedia.org/articles/acoustic-schwannoma. Accessed May 17, 2015.

2. Berry M. Diagnostic radiology. New Delhi: Jaypee Brothers Medical Publishers; 2006.
 

28-year-old male presented with sensorineural hearing loss for two months.

Image IQ: 28-year-old, Sensorineural Hearing Loss

55-year-old male presented with chief complaints of swelling in the left leg for 4 months.

Plain radiograph of the left leg shows a large soft tissue mass in the region of the proximal femur with rings and arcs pattern of calcification and destrcution of the underlying bone.

Chondrosarcoma is a malignant tumor of chondrogenic origin that arises from chondroblasts and collagenoblasts. It is the third most common primary malignant bone tumor, following multiple myeloma and osteosarcoma and making up about 10% of all primary malignant bone tumors.

 Symptoms: Pain or swelling, or a combination of both.

Location: Most common sites are the pelvis and proximal femur (50%); other sites include proximal humerus (10%), ribs (15%), scapula (6%), distal femur and proximal tibia (7%), and craniofacial bones and sternum (5%).

 Large, radiolucent, round or oval lesion with poorly defined margins.

 Contours of the bone are enlarged or expanded. Metaphysis or diaphysis of long bones.

 Scalloping of the inner cortex (endosteum) is caused by the lobular out lines of the tumor.

 Cortex may be extensively eroded- indicates an advanced stage.

 Matrix of the lesion may have circular radiolucencies that represent large lobules of cartilage, imparting a bubbly appearance.

 Foci of irregularly scattered calcification in the tumor called as popcorn, fluffy, stippled, cotton wool, rings, and broken rings. 

 Soft tissue mass with heterogeneous contrast enhancement.

 T2 hyperintense signal in the non mineralized/calcified portions is highly suggestive of a chondroid matrix. Most demonstrate heterogeneous moderate to intense contrast enhancement.

1. Yochum T, Rowe L. Yochum and Rowe's essentials of skeletal radiology. Philadelphia, PA: Lippincott Williams & Wilkins; 2005.

2. Datir A. Chondrosarcoma .Radiology Reference Article. Radiopaedia.org Retrieved March 22, 2015. Available from: http://radiopaedia.org/articles/chondrosarcoma.

55-year-old male with swelling in left leg for four months.

Image IQ: 55-year-old Male, Swelling in Leg

Case History: A male child of normal intelligence belonging to a nonconsanguineous marriage was sent to the radiology department for skeletal survey in view of coarse facial features, short stature, and spinal deformity.

Slideshows

Case History: Skeletal survey for coarse facial features, short stature, spinal deformity in male child of normal intelligence.