High-grade desmoplastic infantile astrocytoma in a 1-year-old child with Down's syndrome: a case report.

Background: Down's syndrome is the most common chromosomal abnormality in humans. It has been associated with central nervous system tumors such as primary acute lymphoblastic leukemia and germinomas, but desmoplastic infantile astrocytoma has not yet been reported with Down's syndrome. Desmoplastic infantile astrocytoma is a rare intracranial tumor that mostly occurs in the first 2 years of life. It usually presents as a large, aggressive tumor with both solid and cystic components. Genetically, it has been linked to the BRAF V600E mutation. Despite the rapid growth pattern, it usually has a favorable prognosis after neurosurgical excision. The presence of this extremely rare, genetically linked tumor, and its combination with Down's syndrome, the most common human genetic defect, makes this a very novel clinical presentation. It also raises a very research-worthy question of an undiscovered link between these two genetic disorders.

Case Presentation: In this case, we report a 1-year-old Pakistani origin male child with Down's syndrome, who presented with progressive macrocephaly and developmental regression over the last 2 months. He was unable to sit by himself, and had lost his handgrip bilaterally. Down's Syndrome was diagnosed soon after birth, based on typical facial features and presence of palmar crease, and later confirmed karyotypically for Trisomy 21. Upon presentation, initial blood tests did not show any abnormality. Magnetic resonance imaging of the brain was done, and showed a mixed intensity cystic mass with solid dural component posteriorly in the right parieto temporo occipital region. Craniotomy was performed, and about 85% of the tumor mass was excised. Histological examination and immunochemistry confirmed the suspected radiological diagnosis of desmoplastic infantile astrocytoma. After surgical excision, our patient gradually reacquired his previously regressed developmental milestones. Unfortunately, the remaining mass, which could not be excised due to its attachment to the highly vascular dura mater, showed regrowth on repeat brain magnetic resonance imaging. As his parents did not consent to further surgery, chemotherapy was offered as the next treatment option to prevent tumor regrowth.

Conclusions: This case report highlights the need for more case data and research to understand desmoplastic infantile astrocytoma, and their genetic correlation with Down's syndrome. From a clinical standpoint, since desmoplastic infantile astrocytoma has a good postresection prognosis in a majority of early-diagnosed clinical cases, pediatricians, radiologists, and pathologists should consider desmoplastic infantile astrocytoma in their initial differential diagnosis in Down's syndrome patients with macrocephaly and developmental regression during the first 2 years of life.