PART TWO
Diagnostic Cytology
Fig. 18.44 Giant cell tumor of bone. Giant cell tumor of bone in (A) May-Grunwald-Giemsa (B) H&E-, and (C) Papanicolaou-stained FNABs. The stromal cells
are best seen in the Diff-Quik preparation in this biopsy and the giant cells can have up to 50 nuclei (MP x HP).
chordoma is characterized by a proliferation of large cells with
vacuolated cytoplasm (physaliphorous cells) in nests, cords,
or sheets embedded within a myxoid stroma (Fig. 18.45A).
The FNAs of chordomas are usually moderately to highly cel-
lular. The cellular component is composed of large, mono- or
binucleated physaliferous cells arranged as single cells, loose
clusters, and concentric pearl-like structures. The physaliferous
cells have abundant highly vacuolated cytoplasm with centrally
located nuclei and smooth nuclear membranes. The chroma-
tin are granular with a salt-and-pepper appearance and small
nucleoli is usually noted. Small, rounded, uniform cells; and
short spindle-shaped cells may be present in addition to the
physaliferous cells.175 Intranuclear inclusions, mitotic figures,
and anisonucleosis can be seen.176,177 Air-dried, Giemsa-stained
preparations show a distinctive, but nonspecific, metachro-
matic staining of the background fibrillary matrix, which can
be present surrounding individual cells (Fig. 18.45B). The
matrix is lightly eosinophilic on H&E stain and pale blue to
green-gray on Papanicolaou stain.178 Cartilaginous stroma can
be seen in the chondroid chordoma variant of chordoma.179
An associated high-grade sarcoma can be seen in dedifferenti-
ated chordoma.180 Immunohistochemically, the neoplastic cells
are immunoreactive for S-100 protein, cytokeratin, and epi-
thelial membrane antigen (EMA), but are usually negative for
carcinoembryonic antigen (CEA). The cytological differential
diagnosis includes chondrosarcoma, liposarcoma, and meta-
static adenocarcinoma.
Chondrosarcomas
are negative for
epithelial markers and most adenocarcinomas show immuno-
reactivity for CEA.
Key features of chordoma
• Large, mono- or binucleated physaliferous cells
with vacuolated cytoplasm, centrally located
nuclei, granular chromatin pattern, and a small nu-
cleoli;
• Presence of small, round, uniform cells and short
spindle-shaped cells;
• Metachromatic staining of background fibrillary
matrix on air-dried, Giemsa-stained preparations,
which surrounds individual cells;
• Intranuclear inclusions, mitotic figures, and aniso-
nucleosis; and
• Cartilaginous stroma present in chondroid variant of
chordoma.
500
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