Malignant GCT.
Although GCTBs are usually benign, malignant GCTBs can be seen
accounting for 1% - 2% of cases [19,26,27]. They differ clinically
from the usual GCT, showing masses that grow fast with signs of local
invasion and associated axillary adenopathy. They show higher rates of
local recurrence [4,28,29]. The breast can also be secondarily
involved with metastasis from primary malignant GCT elsewhere.
Recurrence and metastasis, however, can occur with histologically benign
or atypical GCTs [14,30]. When metastasis occurs, the most common
sites are lungs and bones and less commonly liver, bowel, breast,
thyroid, heart, pancreas, spleen, retroperitoneum, pharynx, mouth, neck,
and brain [3]. There is no staging system for malignant GCTB
[31].