Histology:
On macroscopy GCTBs are firm, solitary masses, some of them
circumscribed, with a capsule, but they frequently show an infiltrative
growth pattern with non-circumscribed margins [14]. They are
typically homogenous with a color ranging from white to tan [14].
They can be associated with fibrosis in 40% of cases [43]. When
non-encapsulated, they may infiltrate into the surrounding tissues like
fibrous tissue, adipose tissue and pectoralis major muscle [14]. Due
to this growth pattern, GCTBs may resemble invasive breast carcinomas
[12,16]. On microscopy GCTBs show an infiltrative growth pattern in
nests, cords, or sheets of large polygonal and occasionally spindled
cells with abundant eosinophilic, finely granular cytoplasm and small
nuclei surrounded by sclerotic stroma [14,32]. GCTs have
Pustulo-ovoid bodies of Milian, which are large granules with clear
halos [14,32]. The granules are strongly period acid-Schiff (PAS)
positive, and they represent lysosomes. Nuclei have dense chromatin, are
relatively small, and are centrally placed [1].