Intestinal Carcinoid

CT Enteroclysis of 55 year old male came with history of dull aching intermittent pain abdomen with episodes of subacute intestinal obstruction. The axial contrast enhanced CT enteroclysis image shows a well defined brilliantly enhancing focal lesion seen in the right iliac fossa causing significatn luminal narrowing of one of the ileal loop. Rest of the structures of abdomen were unremarkable. The coronal refoamatted image better shows the relation with the iliac vessels.

Histology: Carcinoid tumors are relatively rare neuroendocrine tumors. They constitute approximately 2% of all gastrointestinal tumors. Carcinoid tumors belong to a category of tumors called apudomas (amine precursor uptake and decarboxylation tumors) because they arise from endocrine amine precursor uptake and decarboxylation cells that can be found throughout the gastrointestinal tract and in other organs such as the pancreas and the lung. Microscopically, carcinoid tumors are made up of small round regular cells containing a round nucleus and clear cytoplasm. A prominent nucleolus is often present. he presence of elevated excretion of 5-hydroxyindoleacetic acid (5-HIAA) is suggestive of a functioning carcinoid tumor.

Clinical Presentation : Carcinoid tumors are characteristically slowly growing tumors that may go unrecognized for many years. The symptoms are often vague, such as intermittent abdominal pain. The diagnosis is typically not made until the patient undergoes exploratory surgery. These tumors most commonly occur in the fifth or sixth decade of life. The average time from the onset of symptoms to the diagnosis exceeds 9 years. In many cases the diagnosis is not suspected until the patient develops carcinoid syndrome, which typically does not occur until the disease has spread to the liver. However, only 10% of patients will develop the carcinoid syndrome, which is more common with tumors of the ileum and jejunum but also occurs with bronchial and other carcinoid tumors.

Radiology: Small-bowel carcinoid tumors are neuroendocrine neoplasms that present unique imaging challenges. In their early stages, the tumors are small and confined to the bowel wall. Small-bowel series and enteroclysis may be more sensitive for detection than CT or MRI. As the tumor grows, extension outside the involved bowel loop may occur, with infiltration of the mesentery and desmoplastic reaction, which results in a characteristic appearance on small-bowel contrast examinations and cross-sectional imaging. In patients in whom there is a high clinical suspicion of carcinoid tumor but inconclusive barium studies or CT, angiography can be performed and may show the submucosal mass because of its vascularity.Alternatively, in this situation, CT angiography may also be used to localize the mass on the basis of its vascularity and in many cases may obviate conventional angiography.

In addition to contrast studies and CT, nuclear medicine techniques using indium-111– or iodine-123–labeled octreotide or iodine-131–labeled metaiodobenzylguanidine (MIBG) are helpful for diagnosing and locating carcinoid tumors and identifying their metastases.

Surgery is the mainstay of treatment.

Confluent Hepatic Fibrosis (CHF)

Multiphase CT scan of 13 year old male patient with known case of cirrhosis, non contrast image showing atrophy of left lobe with capsular retraction. Arterial phase image does not show any enhancement. Venous phase image shows faint wedge shaped enhancement in segment IVa (arrow head) and the delayed image shows progressive incresed and persistant enhancement in segment IVa (arrow). Rest of the liver shows lace like enhancement. No mass effect or vascular displacement. The findings are consistant with Confluent hepatic fibrosis (CHF).

Pathology:

CHF Can be seen on imaging in approximately 14% of patients with advanced cirrhosis who are candidates for liver transplantation. It is associated with volume loss seen as retraction of overlying hepatic capsule or total shrinkage of segment or lobe.

Imaging Findings:

CHF is seen incidentally in patients with advanced cirrhosis who undego pretransplant imaging or imaging to ruleout hepatocellular carcinoma. Best diagnostic clue for CHF is pre-contrast CT showing hypo attenuating lesion with volume loss that becomes isoattenuating or minimally hypoattenuating at post-contrast CT, especially if wedge-shaped, located in medial segment of left lobe &/or anterior segment of right lobe, in patients with advanced cirrhosis. In our case the non contrast images are not showing typical hypoattenuation lesion. Wedge-shaped lesions radiate from porta hepatis & extend tohepatic capsule. Peripheral lesions are remote from porta hepatis. Lobar or segmental involvement, most commonly in lateral segment of left lobe. Retraction of overlying capsule seen in 90% cases.

The lesions are isoattenuating on post contrast images in 80% and hperattenuating on delayed scans. They show delayed persistent enhancement due to variability in contrast enhancement of confluent fibrosis relates to relative vascularity & extent of fibrosis.

MR imaging does show morphological changes & characteristic locations that suggest diagnosis, but no more so than CT. Lesions appear as regions of hypointense signal relative to adjacent liver parenchyma on T1 imaes and hyperintense on T2 due to prominant edema. They show delayed progressive enhancement on administration of gadolinium.

Differential diagnosis for focal liver lesions with capsular retraction apart from CHF are Cholangiocarcinoma, Treated metastases and sclerosing cholangitis.

Rhinolith

21 year old male presented to ENT specialist complaining nasal mass and nasal block. Patient was reffered for CT scan of para nasal sinuses. Fig a and b shows curvilinear calcific density lesion seen in the right nasal cavity between theinferior turbinate and nasal septum. No soft tissue associated with the lesion. The findings suggestive of rhinolith.

Rhinolith is calcareous concretions around calcinated intranasal foreign bodies within the nasal cavity. Patient may not always gives history of foriegn body insertion in to nasal cavity. It is usually found in the anterior part of the nasal cavity and is usually diagnosed on history and clinical examintion. In such a condition, radiological evaluation is needed for differential diagnosis and to detect any related complications. CT scan is useful in a posteriorly situated mass which may cause difficulties in diagnosis.

On CT scan, it appears as a homogenous, high-density lesion with smooth mineralization.The central portion of the lesion, which may contain organic material, may be of a somewhat lower density, or a foreign-body nidus may be seen. The most important differential diagnosis include haemangioma, osteoma, calcified polyps, enchondroma, dermoid, chondrosarcoma, osteosarcoma, syphilis and tuberculosis. The complications reported are sinusitis, septal perforation, palatal perforation, recurrent otitis media, and recurrent dacryocystitis.

Mineralizing microangiopathy

Lateral radiograph of 14 year old boy who underwent radiotherapy and chemotherapy for right frontal glioma shows linear tram tack calcification in the frontal region.

CT scan of the same patient showed caorse gyral patternn calcification in the roght frontal region with white matter edema in bilateral frontal lobes.

Mineralizing microangiopathy, a distinctive histopathologic process involving the microvasculature of the central nervous system (CNS), is usually seen following combined radiation and chemotherapy for the treatment of CNS neoplasms in childhood. It represents dystrophic calcification within the brain substance, predominantly involves the basal ganglia and subcortical white matter and is well shown by CT. CT typically demonstrates calcification within the basal ganglia and subcortical white matter. MRI, although less sensitive than CT to calcification, The areas of calcification may give paradoxically increased signal on T1-weighted MRI due to a surface-relaxation mechanism, and decreased signal on T2-weighted images. This should be differentiated from Sturge weber syndrome by the clinical presentation and other imaging findings.

Periapical cyst (radicular cyst)

Fig a: OPG of 14 year old male with h/o caries tooth shows subtle oval lytic lesion at the apex of root of second molar tooth.

Fig b: Coronal reformatted image shows well defined cystic lesion at the apex of tooth (arrow) and is better demonstrated by the 3D volume rendering image in fig c (arrow). The features are consistant with periapical cyst.

The periapical (radicular) cyst is the most common odontogenic cyst and results from inflammation secondary to caries or other entities. The peak prevalence of this asymptomatic cyst occurs between the fourth and sixth decades of life. Typically, infection spreads to the apex (root) of the tooth, leading to secondary apical periodontitis, granuloma, or abscess and, finally, cyst formation. The cyst appears as a round or pear-shaped, well-defined radiolucent lesion with sclerotic borders. Most periapical cysts are less than 1 cm in diameter. It is important to note that radiology cannot always help distinguish a granuloma from a cyst.

Ameloblastoma

Ameloblastoma arises from the enamel-forming cells of the odontogenic epithelium that have failed to regress during embryonic development. The tumor most commonly occurs in the posterior mandible, typically in the third molar region, with associated follicular cysts or impacted teeth. The slow growth of the tumor can lead to significant expansion of the mandible. Patients typically present in the third to fifth decades of life with a slow-growing, painless mass. The expansile, radiolucent tumor can be unilocular or multilocular, with a characteristic "soap bubble–like" appearance. CT findings include cystic areas of low attenuation with scattered isoattenuating regions, representative of soft-tissue components. The lesion can also erode through the cortex with extension into the surrounding oral mucosa. In addition, erosion of the roots of adjacent teeth is unique to ameloblastoma and indicates the aggressive behavior of the tumor. However, only histopathologic findings can help determine benignity and the absence of carcinomatous change.

Fungal Sinusitis

PNS Radiograph shows opacification of all the visualized sinuses suggestive of sinusitis. Here it is impossible to differentiate the type of sinusitis. And may be possibel with cross sectional imaging. Non contrast CT Scan axial and coronal reformatted images shows soft tissue density material seen in bilateral maxillary sinuses and in nasal cavity with focal areas of increased attenuation(arrows) suggestive of fungal sinusitis.

Fungal infections of the paranasal sinuses are uncommon and usually occur in individuals who are immunocompromised. However, recently, the occurrence of fungal sinusitis has increased in the immunocompetent population. Distinguishing invasive disease from noninvasive disease is important because the treatment and prognosis are different for each. The most common pathogens are from Aspergillus and Mucor species. Aspergillosis can cause noninvasive or invasive infections. Invasive infections are characterized by dark, thick, greasy material found in the sinuses. Invasive infections can cause tissue invasion and destruction of adjacent structures (eg, orbit, CNS). Noninvasive infections cause symptoms of sinusitis, and the sinus involved is opacified on radiographic studies. Routine cultures from the sinuses rarely demonstrate the fungus. Thus cross sectional imaging is the main stay of diagnosis of fungal infection. The demonstration of focal or diffuse areas of increased attenuation in paranasal sinus soft-tissue masses on unenhanced CT scans strongly suggests fungal involvement. MR imaging was even more sensitive than CT in identifying a fungal concretion in a limited number of patients. On the basis of preliminary studies, decreased signal intensity on T1 and very decreased signal intensity on T2-weighted MR images seem to be characteristic of mycetomas. This may be due to the presence of fenromagnetic elements within fungal concretions.