PART TWO
Diagnostic Cytology
Fig. 18.18 Epithelioid angiosarcoma. (A) Histologic section. Epithelioid
cells are represented by large polygonal cells with high N/C ratio,
eosinophilic or amphophilic cytoplasm (H&E x MP). (B) Smear. Pleomorphic
cells with irregular-shaped nuclei containing multiple large nucleoli, and
coarse chromatin. Intracytoplasmic lumen and intracytoplasmic hemosiderin
deposition present (Papanicolaou x HP).
• Multinucleation rare; and
• Vasoformative features.
Key features of epithelioid angiosarcoma
• Cells with irregular-shaped nuclei containing multiple
large nucleoli and coarse chromatin;
• Multinucleation common;
• Cytoplasm with microvacuolization, especially on
Diff-Quik-stained slides;
• Vasoformative features; and
• Intracytoplasmic lumina possible.
Other
intramuscular Myxoma
Intramuscular myxomas are benign soft tissue tumors com-
posed of spindle cells with minimal atypia associated with
abundant myxoid stroma. They have a predilection for female
patients and the most common sites include thigh, shoulder,
buttocks, and upper arm. It occurs mostly in patients between
40 and 70 years old. The main symptom is a painless soft tissue
mass. Radiological studies show a bright lesion on T2-weighted
images. The histological sections of intramuscular myxoma
are characterized by a population of bland spindle and stel-
late-shaped cells with eosinophilic cytoplasm and small nuclei
embedded in abundant myxoid stroma. Sparse capillary vessels
are noted in the stroma. The cytological preparations typically
contain few spindle cells associated with an abundant myxoid
extracellular material. The spindle cells have long cytoplasmic
processes. Nuclei are oval to spindled with fine chromatin and
inconspicuous nucleoli. No cells with scalloped nuclei sugges-
tive of lipoblast are present. Capillaries are sparse. The myxoid
material is metachromatic in air-dried, Giemsa-stained slides
and basophilic in Papanicolaou stain.100-104 The differential diag-
noses of myxoma include myxoid schwannoma, neurofibroma,
ganglion cyst, myxoid liposarcoma, fibrosarcoma, malignant
fibrous histiocytoma, and extraskeletal chondrosarcoma. The
malignant lesions show the presence of marked atypia, a feature
not seen in myxomas.
Key features of intramuscular myxoma
• Few spindle cells associated with an abundant myxoid
extracellular material;
• Spindle cells with long cytoplasmic processes;
• Oval to spindle nuclei with fine chromatin and incon-
spicuous nucleoli;
• Sparse capillaries; and
• Metachromatic myxoid material in air-dried, Giemsa
stained slides and basophilic in Papanicolaou stain.
Angiomyxoma
Aggressive angiomyxoma is a large soft tissue neoplasm prone
to local recurrence. They occur predominantly in the pelvis and
peritoneum of females. The peak incidence is the fourth dec-
ade. T2-weighted magnetic resonance imaging and computer-
ized tomography frequently demonstrate a swirled or layered
structure.105 Histologically, angiomyxomas are characterized by
a proliferation of spindle- or stellate-shaped cells and abundant
myxoid stroma associated with a prominent vascular compo-
nent. The vessels are represented by large, thick-walled vessels
without an arborizing pattern. FNAB smears are hypocellular
and contain scattered spindle cells with bipolar cytoplasmic
processes, as well as bland stellate cells. The nuclei are fusiform
to oval with bland chromatin pattern. These cells are present in
a background composed of abundant myxoid stroma.105,106 The
differential diagnosis includes other myxoid neoplasms, partic-
ularly myxoid liposarcoma. Myxoid liposarcoma is frequently
associated with an arborizing vascular network not seen in
aggressive angiomyxoma. Nonetheless, open surgical biopsy is
recommended in these lesions due to overlapping features with
other myxoid lesions.
Key features of angiomyxoma
• Hypocellular specimens;
• Scattered spindle cells with bipolar cytoplasmic
processes and bland stellate cells;
• Fusiform to oval nuclei with bland chromatin pattern;
and
• Abundant myxoid stroma.
486
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