Source 1: WHO Class Skin Tumors
pgs: on-line version
Notes: 4th edition
Source 2: 2018 SEER Manual
Reportability--Skin: Is malignant proliferative trichilemmal tumor (PTT) reportable, and if so, do we apply the matrix rule and code it to 8103/3? A literature search reveals these do exist, but are extremely rare.
Malignant PTT (8103/3) of the skin is not reportable. A neoplasm originating in the skin with histology coded to 8103 is not reportable. See 1.b.i. on page 7 in the 2018 SEER manual for a complete list, https://seer.cancer.gov/manuals/2018/SPCSM_2018_maindoc.pdf