Encephalic Lipoma (tubulonodular type) with neuroglial component associated with partial agenesis of the Corpus Callosum. The patient was discharged home without further deficit. Follow-up MRI displayed remaining tumor in the location. The patient remains under clinical observation for mass re-growth and other systemic lesions.
Intracranial lipomas are infrequent Central Nervous System(CNS) lesions with an incidence that ranges between 0.08 to 0.2% of autopsied cases and between 0.06 to 0.3% among those found during imaging,(3) but according to others this frequency can raise up to 0.4%.(12) Although these lesions are considered grade I mesenchymal, non-meningothelial tumors according to the World Health Organization,(12) their origin is not clear and the idea of a primary malformation is still accepted. In fact, their origin may arise in the abnormal persistence and abnormal differentiation of the primitive meninx.(5,16) These kind of lesions are more frequently detected as a single entity, however, they can also be a component of "encephalocraniocutaneous lipomatosis" a rare neurocutaneous syndrome.(7)
By imaging studies intracranial lipomas are frequently located in the midline, usually in the supratentorial compartment, and more precisely they tend to be interhemispheric in the anterior corpus callosum.(9,12,16) In fact, pericallosal lipomas as a single entity are usually divided into two groups: curvilinear and tubulonodular;(1,2,15,16). The former are thin, posteriorly located in the corpus callosum, and have low incidence of associated anomalies;(2,15). On the other hand, tubulonodular lipomas are located anteriorly, and are associated with a high incidence of facial defects and/or encephaloceles.(15) On MRI, characteristically these lesions are homogenous, and show hyperintensity on T1-weighted images and hypo or isointensity on T2.(5)
Clinically patients can be asymptomatic, present with recurrent headaches,(3) show mental retardation(8) or can present with focal or generalized epilepsy,(4,6) which has been regarded by some as the most frequent presentation,(11) but this has more recently been challenged.(13)
In our case, the patient presented with three lesions: a subcutaneous frontal lipoma independent of the cranial vault, an intracranial tubulonodular lipoma mixed with neuroglial tissues arising in the interhemispheric fissure, and partial agenesis of the posterior corpus callosum. There was no history of mental retardation or epilepsy.
In terms of the histological assessment, this case showed typical features of a mature lipoma intermingled with neuroglial tissue imparted by the presence of neuropil showing reactive astrocytes and mature neurons with glial satellitosis. Reports of lipomas arising in that location with or without agenesis of the corpus callosum are not abundant and most of the lesions described are composed only of typical mature lipomatous tissue;(18,17,12) and these lesions are usually sharply demarcated from cortex,(10) or but others may show myelo-lipomatous differentiation (i.e., with hematopoietic elements).(14)
In conclusion, we report a case of an asymptomatic child with partial agenesis of the corpus callosum and two lipomas, an extracranial one with mature lipomatous tissues only and a second intracranial interhemispheric frontal mass with a mixture of mature lipomatous and neuroglial tissues.
Contributed by Laura Aón Bertolino, MD; Pía Lépore, MD2; Mónica Carassai, MD, Roberto González, MD; Gustavo Sevlever, MD, PhD; Miguel A. Riudavets, MD.