corpus callosal lipoma- case report

a 39 yr old male presenting with vague headache for a month was advised MRI brain
findings: lipoma involving splenium with partial agenesis.

Corpus callosal lipoma

Lipomas of corpus callosum

Lipomas of corpus callosum are morphologically 

classified into two groups: anterior lipomas are 

indicated as tubulonodular, usually bigger than 2 cm 

and frequently associated with hypogenesis/agenesis 

of corpus callosum, frontal lobes anomalies, frontal 

encephalocele, calcifications, and/or ocular anomalies. 

Posterior lipomas are indicated as curvilinear, they are 

thin and usually lay on splenium; they are less frequently 

associated with corpus callosum anomalies and/ or other 

encephalic anomalies.

Association with hypogenesis/agenesis of corpus callosum 

is frequent, being present in 90% of anterior lipomas and 

in 30% of posterior lipomas.

A pure (isolated) lesion of corpus callosum probably 

does not cause symptoms. 

Clinical manifestations like seizures and mental disorders must be attributed 

to concomiting nervous tissue anomalies. Epilepsy 

is one of the most frequent symptom: when present it 

appears before the age of 15, is often partial and severe.

Lipomas of corpus callosum can also cause 

obstructive hydrocephalus.

In hypogenesis/agenesis of corpus callosum, nervous 

fibers that do not cross the interemispheric fissure, run 

parallel to it, along the medial walls of both lateral 

ventricles (Probst’s bundles), deforming the III ventricle 

and the lateral ventricles.

It is not yet clearly explained the eventual mechanism 

that could deform the posterior segments of ventricular 

cavities. It was hypothesized that posterior fibers that don’t 

cross midline, could interfere with correct development 

of parietal and occipital white matter, being associated 

with hypogenesis of hippocampus.

Diagnosis accidentally occurs during diagnostic 

procedures in case of an encephalic disorder.Sonographic 

prenatal diagnosis is possibile at 26 weeks of gestation.

On CT scans, lipomas appear as areas of hypodensity, 

that can contain calcific hyperdensities, so, these 

aspecific aspects, prospect differential diagnosis with 

dermoid cysts and teratomas. MRI scans 

do not leave doubts, infact fat signal is characteristically 

hyper in T1w and T2w sequences, and in FATSAT 

sequences it is suppressed. Angiography shows 

displastic cerebral arteries involved in the lesion, but not 

compressed or displaced.

There’s no indication to surgical treatment in isolated 

(pure) corpus callosum lesions; on the other hand, 

surgical outcomes are controversial because is difficult 

a complete debulking that spare the nervovascular 

structures involved.

Prognosis and symptoms depends on associated 

malformations. Risks to be considered, above all in 

the evolutive age, are hydrocephalus and epilepsy.

meningioma:plain ct features

Meningiomas are dural based, benign, slow growing tumors.  They are usually solitary lesions and are 8 times more likely to occur in the brain than the spinal cord.  When in the spinal cord, the thoracic spine is affected 80% of the time. On pathology, meningiomas are usually firm, round and well demarcated.  Meningiomas have a peak incidence in the 5th and 6th decades of life. Presenting symptoms are usually due to mass effect the tumor has on adjacent neural tissue and can include pain, motor or sensory deficits. 
Meningiomas are usually WHO grade I tumors (95%) and treated with surgical excision.   In this case, the patient presented with back pain. She subsequently underwent resection of her tumor without recurrence.
Radiologic overview:
Meningiomas are well circumscribed, strongly enhancing Meningiomas are dural based, benign, slow growing tumors.  They are usually solitary lesions and are 8 times more likely to occur in the brain than the spinal cord.  When in the spinal cord, the thoracic spine is affected 80% of the time. On pathology, meningiomas are usually firm, round and well demarcated.  Meningiomas have a peak incidence in the 5th and 6th decades of life. Presenting symptoms are usually due to mass effect the tumor has on adjacent neural tissue and can include pain, motor or sensory deficits. 

Meningiomas are usually WHO grade I tumors (95%) and treated with surgical excision.   In this case, the patient presented with back pain. She subsequently underwent resection of her tumor without recurrence. 

Radiologic overview:
Meningiomas are well circumscribed, strongly enhancing lesions.  On non-enhanced CT, meningiomas are difficult to recognize and usually isodense to mildly hyper dense when compared to surrounding brain parenchyma.  With contrast, meningiomas enhance homogeneously.  On T1 and T2 weighted images, meningiomas are Iso intense in relation to the spinal cord.  Some meningiomas are well vascularized and may demonstrate flow voids on T2 images.  Meningiomas have well defined borders and do not invade adjacent neural tissue. 

In this case, there is a solitary, intradural, extramedullary, homogeneously enhancing lesion in the mid-thoracic spinal cord.  In an older female patient, meningioma is the likely diagnosis.  Other intradural, extramedullary lesions include schwannoma, drop metastases, epidermoid, arachnoid cyst, and paraganglioma. 
Schwannomas are nerve sheath tumors and have imaging characteristics similar to meningiomas.  They usually occur in younger patients and can have a dumbbell shape as the tumor encases the nerve root across the neural foramen. In drop metastases, multiple contrast enhancing lesions are seen in the cord. Arachnoid cysts can cause mass effect similar to meningiomas, but are fluid filled structures that demonstrate no contrast enhancement. Epidermoid cysts are lobulated structures that minimally enhance and rarely occur in the spine. Paragangliomas rarely occur in the spine and occur in the cauda equina when they do.
Key points:

• Meningiomas are intradural, extramedullary, well circumscribed, homogeneously enhancing lesions.
• Meningiomas are slow growing tumors that compress but do not invade the adjacent neural tissue.
• Presenting symptoms are nonspecific and related to the mass effect caused by the meningioma.
• Other intradural, extramedullary lesions include schwannomas, arachnoid cysts, epidermoid cysts, and drop metastases.

Interesting case: Sacrococcygeal Teratoma

Sacrococcygeal teratoma (SCT) is a teratoma (a kind of tumor) located at the base of the coccyx (tailbone). It is thought to be a derivative of the primitive streak.

Natural history

SCT is seen in 1 in every 35,000 live births, and is the most common tumor presenting in newborn humans. Most SCTs are found in babies and children, but SCTs have been reported in adults and the increasingly routine use of

prenatal ultrasound exams has dramatically increased the number of diagnosed SCTs presenting in fetuses. Like other teratomas, an SCT can grow very large. Unlike other teratomas, an SCT sometimes grows larger than the rest

of the fetus. Sacrococcygeal teratomas are the most common type of germ cell tumors (both benign and malignant) diagnosed in neonates, infants, and children younger than 4 years.SCTs occur more often in girls than in boys; ratios of 3:1 to 4:1 have been reported.

Historically, sacrococcygeal teratomas present in 2 clinical patterns related to the child’s age, tumor location, and likelihood of tumor malignancy. With the advent of routine prenatal ultrasound examinations, a third clinical patternis emerging.

• Fetal tumors present during prenatal ultrasound exams, with or without maternal symptoms. SCTs found during routine exams tend to be small and partly or entirely external. The internal SCTs are not easily seen via ultrasound, unless they are large enough to reveal their presence by the abnormal position of the fetal urinary bladder and other organs, but large fetal SCTs frequently produce maternal complications which necessitate non-routine, investigative ultrasounds.

• Neonatal tumors present at birth protruding from the sacral site and are usually mature or immature teratomas.

• Among infants and young children, the tumor presents as a palpable mass in the sacropelvic region compressing the bladder or rectum.These pelvic tumors have a greater likelihood of being malignant. An early survey found that the rate of tumor malignancy was 48% for girls and 67% for boys older than 2 months at the time of sacrococcygeal tumor diagnosis, compared with a malignant tumor incidence of 7% for girls and 10% for boys younger than 2 months at the time of diagnosis. The pelvic site of the primary tumor has been reported to be an adverse prognostic factor, most likely caused by a higher rate of incomplete resection.

• In older children and adults, the tumor may be mistaken for a pilonidal sinus, or it may be found during a rectal exam or other evaluation.

Diagnosis

During prenatal ultrasound, an SCT having an external component may appear as a fluid-filled cyst or a solid mass sticking out from the fetus' body. Fetal SCTs that are entirely internal may be undetected if they are small; detection (or at least suspicion) is possible when the fetal bladder is seen in an abnormal position, due to the SCT pushing other organs out of place.

At birth, the usual presentation is a visible lump or mass under the skin at the top of the buttocks crease. If not visible, it can sometimes be felt; gently prodded, it feels somewhat like a hardboiled egg. A small SCT, if it is entirely inside the body, may not present for years, until it grows large enough to cause pain, constipation and other symptoms of a large mass inside the pelvis, or until it begins to extend out of the pelvis. Even a relatively large SCT may be missed, if it is internal, because the bony pelvis conceals and protects it. Mediastinal tumors, including

teratomas, are similarly concealed and protected by the rib cage.

Some SCTs are discovered when a child begins to talk at about age 2 years and complains of their bottom hurting or feeling "poopy" when they ride in a car seat.

Other tumors can occur in the sacrococcygeal and/or presacral regions and hence must be ruled out to obtain a differential diagnosis. These include extraspinal ependymoma, ependymoblastoma, neuroblastoma and rhabdomyosarcoma.

Smaller SCTs with an external component, seen in prenatal ultrasounds or at birth, often are mistaken for spinabifida. Cystic SCT and terminal myelocystocele are especially difficult to distinguish; for more accurate diagnosis,

MRI has been recommended.

SCTs are classified morphologically according to their relative extent outside and inside the body:

• Altman type I — entirely outside, sometimes attached to the body only by a narrow                stalk

• Altman type II — mostly outside

• Altman type III — mostly inside

• Altman type IV — entirely inside; this is also known as a presacral teratoma or retrorectal teratoma

The Altman type is significant in the contexts of management of labor anddelivery, surgical approach, and complications of SCT. Serial ultrasound and MRI monitoring of SCTs in fetuses in utero has demonstrated that the Altman type can change over time. As the tumor grows, it can push between other organs and through the perineum to the body surface where the tumor appears as a bulge covered only by skin. Sometimes, the tumor bulge later slips back inside the perineum.

Interesting case: Dentigerous cyst

Dent igerous   cysts   are   the   second most   common

odontogenic cysts after radicular cysts .  They are

benign odontogenic   cysts   that   are   associated with  the

crowns of permanent unerrupted teeth;  usually single in

occurrence and located in the mandible. Although most

common discovered in the second and third decades, they

may be found at any age