Desmoplastic myxoid tumor of the pineal region, SMARCB1-mutant

Last revised by Dr Daniel J Bell on 06 Jan 2022

Desmoplastic myxoid tumor of the pineal region, SMARCB1-mutant is a rare and recently described type of pineal parenchymal tumor encountered in adults.

Desmoplastic myxoid tumor of the pineal gland SMARCB1-mutant occurs in adolescents and young adults (mean age of diagnosis 40 years old) with a slight predominance in females (M:F ratio of 3:4)1.

Its characteristics are still uncertain since the number of cases is limited. Desmoplastic myxoid tumor of the pineal gland SMARCB1-mutant shares with atypical teratoid/rhabdoid tumors (AT/RT) the mutation of the SMARCB1 gene, although it has different histopathological and clinical features 1,2.

Desmoplastic myxoid tumor of the pineal gland SMARCB1-mutant usually demonstrates spindled and epithelioid cells in a desmoplastic stroma alternating with a myxoid matrix. Unlike atypical teratoid/rhabdoid tumors, it does not present brisk mitotic activity and necrosis 1,2.

Similarly to atypical teratoid/rhabdoid tumors, desmoplastic myxoid tumor of the pineal gland SMARCB1-mutant displays loss of nuclear SMARCB1/INI1 protein expression. Ki-67 index ranges from 2% to 15% 1.

Desmoplastic myxoid tumor of the pineal gland SMARCB1-mutant is indistinguishable from other pineal tumors 2,3.

  • T1: hypointense
  • T2/FLAIR: hyperintense
  • T1 C+ (Gd): strong enhancement 

Data about treatment and prognosis of the SMARCB1-mutant type of tumor are still limited. Surgical resection is the treatment of choice. Chemotherapy and radiotherapy have been employed in some cases 2

The differential diagnosis generally includes other pineal parenchymal tumors.

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