Udit Chauhan

Lhermitte-Duclos Disease: Diagnosis on MRI, MR Spectroscopy, CT and Positron Emission Tomography

A 30-year-old male patient presented with progressive occipital headache since one year with no associated nausea, vomiting or gait disturbance. Neurological examination revealed negative Rhomberg’s sign. Computed tomography revealed non-enhancing hypodense mass in right cerebellar hemisphere compressing fourth ventricle with obstructive hydrocephalus, however it was inconclusive. Afterwards, MRI was performed which revealed right cerebellar mass with striated hypo and iso intense signal on T1W images, hyper and iso intense signal on T2W images. Mass was compressing fourth ventricle postero-inferiorly with obstructive hydrocephalus. Associated inferior tonsillar herniation into upper cervical canal was also noted [Table/Fig-1,​,22]. [Table/Fig-1]: T2W axial (A) & FLAIR (B) coronal images reveals right cerebellar mass (arrows) with alternate bands of hyperintense and isointense signal giving “tiger stripes” appearance with mass effect over cisterna magna & 4th ventricle ... [Table/Fig-2]: T1W sagittal image reveals alternating bands of relative isointense and hypointense signal within the lesion (arrow) with mild inferior tonsillar herniation Proton MRS showed reduced NAA, Choline peaks. Cho/Cr and NAA/Cr ratios were within normal limits [Table/Fig-3]. On Flurodeoxyglucose (FDG) Positron emission tomography (PET) and PET-CT examinations the mass lesion showed evidence of hypermetabolism [Table/Fig-4,​,55]. [Table/Fig-3]: MRS image reveals reduced peaks of NAA and choline, decreased Cho/Cr ratio (0.65). NAA/Cr (1.02) & NAA/Cho (0.94) ratios were also reduced compared to normal [Table/Fig-4]: PET reveals increased FDG uptake in the lesion suggesting hypermetabolism (arrow) [Table/Fig-5]: PET, CT reveals increased FDG uptake by the right cerebellar mass (arrow) Considering diagnosis of Lhermitte-Duclos disease, Ultrasound and CT-scan of chest and abdomen were done, but they did not reveal any abnormality hence ruling out features suggesting Cowden Syndrome. Patient was operated and avascular mass was resected with free margins and sent for histopathological examination. HPE revealed WHO grade-I dysplastic cerebellar gangliocytoma according to criteria for the diagnosis of Lhermitte-Duclos disease. Postoperative course was uneventful and patient was discharged within 1 week after surgery without any neurological deficit. First described in 1920 [1] by Lhermitte and Duclos, Lhermitte Duclos disease (LDD) (dysplastic gangliocytoma) is a rare disorder of uncertain pathogenesis characterized by disarrangement of normal cerebellar laminar cytoarchitexture. This entity has been described by variety of terms like granular cell hypertrophy, ganglioneuroma and gangliocytoma dysplasticum [2]. LDD is found to be associated with Cowden syndrome in 40% cases. Cowden syndrome is also known as multiple hamartoma syndromes, a rare autosomal dominant condition characterized by multiple hamartomas and neoplasms of ectodermal, mesodermal and endodermal origin [3]. LDD can also be accompanied by megalencephaly, hydromelia, heterotopia, microgyria, polydactyly, leontiasis ossea and multiple haemangiomas [2]. Our patient did not show any features of this syndrome. Although LDD usually occurs in third or fourth decades, reported age ranges from newborn to 74 years [3]. Clinically, LDD typically presents with findings of increased intracranial pressure in young adults. Many patients suffer from headache due to increased intracranial pressure caused by mass effect and obstructive hydrocephalus. Nausea, vomiting, visual disturbance and cerebello-vestibular symptoms can also be seen [3]. Classical MRI findings of LDD is described as especially unilateral, non enhancing hemispheric mass with layered appearance consisting of alternating bands of relative iso-, and hypointensity to normal brain on T1W, and relative hyper and iso intensity on T2W images [3]. Wolansky et al., mentioned that “tiger stripes” appearance is so distinctive that that it is unlikely to be confused with another entity. Non-enhancement is not a rule, since LDD lesions with contrast enhancement have been reported rarely [4]. Our case showed right cerebellar lesion with hemispheric expansion and typical striated pattern resembling tiger stripes on both T1- and T2W images with no contrast enhancement or perilesional oedema. MRS shows some characteristic findings such as decreased NAA with increased lactate peak. Lack of increased Cho/Cr ratio is striking which are in contrast to cerebral tumors where choline levels are raised. Our case showed decrease level of NAA and choline. Cho/Cr ratio was also decreased (0.65). NAA/Cr (1.02) & NAA/Cho (0.94) ratios were also reduced compared to normal. The disease is difficult to diagnose on CT, which shows poorly defined hypodense lesion with no contrast enhancement but may show calcification and thinning of occipital bone. FDG-PET revealed increased 18-FDG uptake within whole right cerebellar lesion suggesting either increased overall cell metabolism or an isolated up regulation in enzyme activity of hexokinase remains unclear. Histological examination reveals typical findings of thickening and hypermyelination of the molecular layer and large pleomorphic cells replacing purkinje and granular cell layers. Demyelination of central white matter of the folia is also observed. Conventional MRI shows characteristic and pathognomic features of LDD, however MRS can provide useful additional information regarding benign nature of this lesion. Hypermetabolism on FDG-PET further supports diagnostic accuracy. Thus imaging can achieve accurate preoperative diagnosis of LDD along with delineation of the margins, thereby enabling complete excision.

Juxtarenal Aortic Pseudoaneurysm – Right Renal Vein Fistula with Circumaortic Renal Collar-Delayed Manifestation of a Gunshot Injury – an Uncommon Entity Diagnosed with CT Angiography

Summary Background Delayed presentation of post-traumatic aortic pseudoaneurysm and its fistulous communication with the right renal vein is a very rare entity. Most of the cases described in literature are due to abdominal aortic aneurysm (AAA) rupture into the left renal vein. To the best of our knowledge, communication with the right renal vein has not been described in published literature. Our patient also had a circumaortic renal collar, which is a rare renal vein anomaly. Aortic pseudoaneurysm, its fistulous communication with the right renal vein and circumaortic renal collar in a single patient is of extremely rare occurrence. Case Report A 29-year-old male presented to the cardiology department with complaints of breathlessness, abdominal pain and hematuria for the last 6 months. On clinical examination there was evidence of audible bruit over the abdomen. He had a past history of a gunshot injury around two years back. CT angiography revealed a large partially calcified pseudoaneurysm arising from the right lateral wall of the abdominal aorta with the neck of the pseudoaneurysm at juxtarenal location with a fistula between the anterior wall of the pseudoaneurysm and the posterior wall of the right renal vein. There was an associated incidental finding of circumaortic left renal vein with gross aneurysmal dilatation of both pre- and retro-aortic part of the renal vein. Conclusions Delayed presentation of aortic pseudoaneurysm with its fistulous communication with the right renal vein is a rare entity. CT angiography is a non-invasive modality for diagnosis of the exact site of communication, length of aneurysm, proximal and distal extent of the affected segment and its relationship with surrounding structures.

Collateral Pathways in Budd Chiari Syndrome- MDCT Depiction

Budd Chiari syndrome (BCS) is a condition arising from hepatic venous outflow tract obstruction (HVOTO) arising at the level of hepatic veins, inferior vena cava, right atrium or a combination of these. It can be classified as primary or secondary depending upon the underlying pathophysiology. Regardless of the cause of HVOTO, there is lack/complete absence of hepatic venous drainage leading to constellation of symptoms pertaining to portal hypertension with radiologically visible intrahepatic and extrahepatic porto-systemic collaterals. The presence of these collateral systems provide imaging diagnostic clue in chronic cases with cirrhosis labelled as chronic liver disease and thereby establishing the primary cause of cirrhosis to be BCS. Current essay aims to provide in depth knowledge of collateral pathways of BCS.

Spontaneous Isolated Dissecting Aneurysm of Distal Celiac Artery- A Rare and Lethal Incidental Finding

Aneurysm of celiac artery is an uncommon occurrence with nearly 180 cases being reported in the literature so far [1]. These have been attributed to traumatic, iatrogenic and inflammatory being amongst few associated etiological factors. Spontaneous isolated dissecting aneurysm of celiac trunk is a rare occurrence with very few cases being mentioned in the published literature. Although the rate of rupture was 72% to 87% during the 1st half of the 20th century, advances in diagnostic imaging and early surgical intervention have reduced the rupture rate to 7% in recent years [1]. Early recognition and urgent intervention is required to prevent fatal complications like intraperitoneal rupture. Authors present a case of isolated spontaneous dissecting aneurysm of distal celiac artery in a fifty five year old male patient with alcoholic cirrhosis.

Intrahepatic ascariasis – Common parasite at an uncommon site

Abstract Bacterial infections of the biliary tree are common infections of the biliary system which frequently lead to life-threatening sepsis. Parasitic infections of the biliary tree like ascariasis are not uncommon. Most adult worms reside into the extrahepatic biliary system. Intrahepatic existence is not commonly described. Urgent recognition of the intrahepatic existence of this common parasite is of paramount importance in order to start timely treatment of this life-threatening infection. Authors described a case of intrahepatic ascariasis in a young male who was diagnosed radiologically and thereafter managed with endoscopic retrograde cholangio-pancreatography and antibiotics.

Tubular Ectasia of Rete Testis with Spermatocele.

A 55-year-old male patient presented with a slowly enlarging, painless, large soft mass lesion in left scrotal sac for 6 month. On clinical examination the mass lesion could not be separated from testis, hence provisional diagnosis of testicular tumour was made. For further evaluation scrotal ultrasound was performed. In the region of the clinically palpable lump, ultrasound revealed a unilocular, well-circumscribed cystic lesion with moderately thick wall and fine internal echoes [Table/Fig-1]. The size of lesion was approximately 4.5 x 5 cm. It was located cranial to testis, partially replacing left epididymis. No internal or peripheral flow was detected on colour Doppler study. Mild fluid was also noted in scrotal sac, which was consistent with hydrocele. Right testis and epididymis were normal. [Table/Fig-1]: Gray scale ultrasound image of left scrotal sac shows a well circumscribed, rounded, unilocular cystic lesion with low level internal echoes located superior to left testis consistent with the diagnosis of spermatocele Ultrasound examination also revealed a cluster of multiple, small, anechoic cysts located in the region of testicular mediastinum [Table/Fig-2]. No solid component or calcification was seen. No evidence of any obvious arterial or venous flow was noted in the cysts on colour Doppler study [Table/Fig-3]. [Table/Fig-2]: Transverse (A), longitudinal (B) gray scale ultrasound images of left testis shows a cluster of multiple small anechoic cystic structures noted in the region of testicular mediastinum with hydrocele [Table/Fig-3]: Transverse colour Doppler ultrasound image of left testis shows numerous small cysts with no colour flow On the basis of characteristic ultrasound and Doppler findings final diagnosis was made of tubular ectasia of rete testis and spermatocele. Because of benign nature of this condition patient was reassured and ask for 6 monthly follow up. Tubular ectasia of the rete testis is a benign clinical entity in which cystic dilation of rete testis results from partial or complete obliteration of the efferent ducts [1]. The obstruction may occur at different levels and may be classified into intra- or extra-testicular. In testicular lesions, the obstruction generally resulting from previous inflammatory episodes like orchitis, while in extra-testicular lesions, traumatic tearing of epididymis, obstruction from epididymitis, spermatoceles and tunica albuginea cyst and post-vasectomy or other scrotal surgeries are the common causes [2]. Typically this condition affects patients older than 50 year of age. Bilateral lesions have been reported in 29 to 69% of cases [3]. Spermatocele and epididymis cysts are commonly associated with this condition. Ultrasonography is usually the first and only modality needed to diagnose this condition. Sonographic findings of tubular ectasia of rete testis consists of a cluster of several anechoic rounded and serpiginous tubular structures located in the mediastinum testis without any solid areas or calcific foci. They do not cause mass effect on the adjacent testicular parenchyma. Colour Doppler shows no arterial or venous flow within cystic lesions [4]. Spermatoceles are common extra-testicular lesions caused by cystic dilation of efferent ductules in the region of head of epididymis. On ultrasonography, it appears as a unilocular or multilocular hypoechoic cystic lesion located superior to and separate from testis. It is usually small in size ranging from 1-2cm in size. However large lesions upto 8 cm in size have been reported in the literature [5]. Spermatocele may show low-level echogenic internal echoes due to proteinaceous fluid containing dead sperms. MRI is usually not indicated because of typical appearance on ultrasound. However, if done in doubtful cases, reveals a cluster of round or serpiginous lesions in the hilum of testis, which appear hypointense TI-weighted and hyperintense on T2- weighted images. The main differential diagnosis includes intra-testicular varicocele and cystic dysplasia of testis. Intra-testicular varicocele is a rare entity, which can give similar appearance on B-mode ultrasonography, however colour Doppler and pulsed Doppler evaluation shows colour flow with characteristic venous spectral waveform that augments during Valsalva maneuver [6]. Cystic dysplasia of testis is thought to be a congenital condition unlike tubular ectasia of rete testis which is an acquired condition. It is seen in children and has similar appearance to tubular ectasia of rete testis [7]. Other differential diagnosis includes epididymal cystadenoma, teratoma, non-Hodgkin’s lymphoma and seminiferous tubules dilatation secondary to testicular neoplasms [1]. Tubular ectasia of rete testis and spermatocele are benign entities With characteristics features on gray scale and colour Doppler examination. This condition should be recognized in older individuals and its awareness can prevent unnecessary investigations and surgical intervention.