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Congress: ECR25
Poster Number: C-22268
Type: Poster: EPOS Radiologist (educational)
Authorblock: S. K. Hadzhiyska, R. Vuchkova, R. Petkov; Sofia/BG
Disclosures:
Simona Krasimirova Hadzhiyska: Nothing to disclose
Ralitsa Vuchkova: Nothing to disclose
Radoslav Petkov: Nothing to disclose
Keywords: Abdomen, Neuroradiology brain, Thorax, CT, MR, Ultrasound, Diagnostic procedure, Genetic defects
Findings and procedure details

In cases where the clinical presentation isn’t sufficient for a conclusive diagnosis, imaging comes in aid with all modalities serving a role. Magnetic resonance imaging (MRI) and computed tomography can both provide a comprehensive and precise evaluation of most, if not all, organ manifestations. Despite their lower specificity and sensitivity (compared to CT and MR), radiography and ultrasound also contribute to this assessment and are excellent in providing first-hand information, for example:

  • On a chest X-ray a radiologist can recognize pneumothorax or reticular interstitial pattern and cystic lucencies based on LAM.
    Fig 1: Chest X-ray of a patient whi bilateral reticular interstitial opacities and cystic lucencies.
    Fig 6: Chest X-ray demonstrates an incerted "pigtail" catheter on the left.

The following part aims to present the most common manifestations, organized by the system or organ affected.

Dermatologic manifestations

Cutaneous lesions are rarely evaluated with imaging techniques, but are worth mentioning because they occur in almost 100% of patients and are among the major features of TSC. Hypomelanotic macules (or ash-leaf spots) are the most frequent and often the first clinical “mark” of the disease. [1] Facial angiofibromas are pink/red dome-shaped papules with a characteristic “butterfly” distribution around the nose. Fibrous plaques of the forehead, ungual fibromas and Shagreen patches are additional skin manifestations, less commonly encountered. [2]

Intracranial manifestations

Cortical (and subcortical) tubers represent benign cortical glioneuronal hamartomas which extend into the underlying white matter and, therefore, can be located anywhere - form cortex to white matter. CT images demonstrate hypoattenuating lesions, that often calcify with the patient’s lifespan. The typical MRI pattern includes low signal intensity on T1-wighted and high signal intensity on T2-wighted images. It is suggested that these findings correlate with clinical neurologic symptoms such as seizures, cognitive impairment and behavioural abnormalities. [1] Subependymal hamartomas are located along the ependymal surface of the lateral ventricles.

Fig 2: Brain CT showing calcified subependymal hamartomas along the ependymal surface of the lateraln ventricles.
Fig 3: Brain CT showing calcified subependymal hamartomas along the ependymal surface of the lateraln ventricles.
They calcify far more often than cortical/subcortical tubers, which makes CT the preferred modality for discovering and monitoring them. MRI images show iso- to hyperintense signals on both T1 and T2-wighted images and variable enhancement. Both cortical/subcortical tubers and subependymal hamartomas occur in about 90% of TSC patients. [2] Subependymal Giant Cell Astrocytomas (SEGA) are benign slow-growing tumors which are known to develop from subependymal hamartomas. SEGAs are hypo- to isointense compared with cortex on T1-weighted images and heterogeneously iso- to hyperintense on T2-weighted images. Although benign these lesions can result in complications such as ventricular obstruction, leading to deteriorating neurological function. Nodules, cysts, foci of gliosis, and hypomyelination constitute various forms of white matter abnormalities (heterotopia), a frequent manifestation of TS. Better evaluated on MRI, they appear as iso- or hypointense areas on T1-weighted images and hyperintense on T2. The only exception are white matter cysts, which differ in their imaging characteristics by showing low attenuation on CT images and are isointense to cerebrospinal fluid on MR images.

Pulmonary manifestations

The most typical pulmonary manifestation is lymphangioleiomyomatosis (LAM), which occurs as a result of diffuse interstitial proliferation of smooth muscle cells.

Fig 4: CT scan of left-sided pneumothorax.
The hallmark feature on CT is numerous diffuse well-defined thin-walled cysts in both lungs. [4] Lung involvement can increase with disease progression and can lead to cough, dyspnea and complications like chylothorax or pneumothorax.
Fig 5: CT images demonstrate numerous thin-walled cystrs with diffuse distribution.
LAM can also occur sporadically – these instances typically entail more extensive lung damage and frequently result in complications compared with TSC-associated LAM. For that reason, it’s important to distinguish both forms (spodaric and TSC-associated). Multifocal Micronodular Pneumocyte Hyperplasia (MMPH) represents a rare pulmonary manifestation characterized by proliferation of type II pneumocytes along alveolar septa. [2] HRCT images show tiny scattered pulmonary nodules (or ground glass nodules) with a random distribution throughout both lungs.
Fig 9: MMPH with solid parenchymal nodule.
Fig 10: MMPH with multiple solid parenchymal nodules.

Cardiac manifestations

Cardiac rhabdomyomas are benign striated muscle tumors, which present (histologically) with “spider” cells a characteristic feature. These masses can be solitary or multiple and occur in up to 80% of patients. [2] The primary diagnostic tool is US (echocardiography), where they appear as well-defined, hyperechoic, homogeneous masses, predominantly involving the ventricles and the ventricular septum. While asymptomatic in most patients, in some cases they can lead to arrhythmia, valvular dysfunction or cardiac failure. Therefore, such individuals require vigilant follow up. Some data has been published, describing myocardial fat foci as a predictive sign of TSC, even though they aren't part of the diagnostic criteria. They typically arise from the left ventricular wall or the interventricular septum, have low (fat) attenuation on CT and are hyperechoic on US. [1]

Abdominal manifestations

Renal angiomyolipomas (AMLs) are common mesenchymal renal neoplasms, that also frequently present in individuals without TSC association.

Fig 7: Abdominal CT scan of lipid-containing lesions in the parenchyma of both kidneys.
In most cases they appear as multiple bilateral masses
Fig 8: Abdominal CT scan of lipid-containing lesions in the parenchyma of both kidneys.
prone to enlargement, which can lead to hemorrhage as a complication. A characteristic feature is low CT attenuation (-20HU), which indicates intratumoral fat content, but not all AMLs are created equal – lipid-poor and lipid-invisible subtypes have been also documented. [3] On CT images, AMLs show variable enhancement patterns depending on their fat content. Studies should be carefully evaluated in lipid-poor and lipi-invisible lesions in order to distinguish them from renal cell carcinoma (RCC) – MRI or percutaneous biopsy should be acquired/performed if necessary. On T1- and T2-wighted images lipid-poor AMLs show hypointense signals compared to certain RCC subtypes (clear cell) which are hyperintense. Although, papillary RCC also demonstrates hypointense signal intensity, but can be distinguished from lipid-poor and lipid-invisible AMLs by its hypovascular structure (i.e. low enhancement pattern). [5] [1] 

AMLs can also be found in other organs such as the spleen or the liver.

Renal cysts are benign, anechoic lesions (on US), typically multiple and affecting both kidneys. Patients remain asymptomatic, except for ones with the polycystic variation who could exhibit complications like hypertension or renal failure. RCC is a rare manifestation (2-3% of cases), but when associated with TS, it affects younger patients and tends to be less aggressive. The classification includes three main histologic subtypes – papillary, chromophobe, clear cell – which show variable enhancement on CT depending on their vasculature.

Other manifestations worth mentioning include multiple musculoskeletal (sclerotic bone lesions)

Fig 11: CT image of a sclerotic bone lesion in the body of a thoracic vertebra.
, ophthalmic (retinal hamartomas), perivascular epithelioid cell tumors (PEComas). The latter represent a group of mesenchymal tumors, which include LAM and AMLs, but also some uncommon manifestations - for example uterine PEComa.
GALLERY