Question: 20190053




#1:   Solid Tumor Rules (2018)
#2:   Histology
#3:   Brain and CNS


Source 1:   2018 Solid Tumor Rules
pgs:   19
Notes:   Malignant CNS, January 2019 update
Source 2:   WHO Class CNS Tumors
pgs:   259-260
Notes:   4th edition


Solid Tumor Rules (2018)/Histology--Brain and CNS:  What is the histology code for a central nervous system (CNS) Ewing sarcoma family tumor with CIC alteration of the right parietal lobe?  See Discussion.


Table 3 (Specific Histologies, NOS, and Subtypes/Variants) lists Ewing sarcoma as a synonym for Peripheral primitive neuroectodermal tumor 9364. Presumably, this is to be used for the reportable malignant peripheral nerve tumors when diagnosed as pPNET or Ewing sarcoma. However, this patient has a type of central (or CNS) primitive neuroectodermal tumor (histology 9473). Table 3 does not list central primitive neuroectodermal tumor (PNET or CPNET) as a valid histology for CNS tumors.

While Table 3 does not list all the possible histologies for the CNS, it currently is not clear how one would arrive at the histology code for a CNS Ewing sarcoma family tumor with CIC alteration, as this is recognized as a new entity for primitive neuroectodermal tumors of the CNS (i.e., PNET, histology 9473) per multiple journal articles. Ewing sarcoma family tumors include both peripheral PNET and central PNET tumors, but to code this histology as a peripheral PNET (9364) in this case seems incorrect when the primary tumor is stated to be of central nervous system origin, not peripheral nervous system origin.


Code as 9364/3.  WHO Classification of Tumors of the CNS, 4th edition, refers to Ewing sarcoma/peripheral primitive neuroectodermal tumor as a tumor of neuroectodermal origin involving the CNS either as a primary dural neoplasm or by direct extension from contiguous bone or soft tissues (such as skull, vertebra, or paraspinal soft tissue).


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