28
Liver and Pancreas
Fig. 28.13 Cavernous hemangioma of the liver. Endothelium-lined
cavernous spaces in spindly stroma. Needle core biopsy (H&E x MP).
is n o w considered part o f a fa m ily o f neoplasm s derived fro m
perivascular e p ith e lio id cells (PE C om as),22,23 inc lu d in g also
clear cell sugar tu m o r o f the lung, clear cell m yom elanocytic
tu m o r o f fa lc ifo rm
lig am ent,
a b d om inop elvic sarcom a o f
perivascular e p ith e lio id cells, and lym p hang ioleiom yom atosis.
T he neoplastic cells o f PECom as were characterized b y expres-
sion o f s m o o th m uscle and m elanocytic (H M B -4 5 ) m arkers.22,23
O n CT scan, hepatic a ng io m yo lip o m a is a circum scribed rou nd
mass up to 20 cm w ith areas o f lo w a tte nu atio n consistent w ith
fat. Preoperative rad iolog ic diagnosis is possible in m ost o f the
hepatic ang iom yolip om as. However, in certain cases it can be
d iffic u lt to disting uish a ng io m yo lip o m a fro m hep atocellular
carcinom as w ith fa tty m etam orp hosis in im aging studies.20 I n
a detailed histo p atho lo g ic study, Tsui and coworkers subcate-
gorized 30 hepatic ang iom yolip om as in to angiom atous, m yo -
m atous (< 10% fa t), lip o m a to u s (> 70% fat), and m ixed types.21
M ixed type was the m ost c om m o n (11 o u t o f 30 cases), com pris-
ing groups o f e p ith e lio id neoplastic cells adm ixed w ith islands
o f adipocytes, ab norm al vessels, and frequently, hem atop oietic
cells. Six were the lip o m a to u s subtype w ith p re d o m in a n tly
adipocytes w ith e p ith e lio id and sh o rt spindle neoplastic cells
webbed between fa t cells. O f the ten m yom atous subtype, five
showed a pure sinusoid al trabecular pattern and com prised
m a in ly e p ith e lio id cells w ith fa t present o n ly as fin e intra cyto -
plasm ic droplets o r as occasional large globules in sinusoids.
M o st o f the e p ith e lio id neoplastic cells were eith er e osin o p hilic
o r clear w ith spider web cell m orp holog y. Three a ng iom yolip o -
mas showed an a lm ost p urely oncocytic appearance, w ith scanty
fa t w ith large p leo m o rp hic e p ith e lio id cells existing as sm all foci,
and spindle cells were u nc om m o n. In histology, the hyperchro-
m atism , p leo m o rp hism , and m oderate m ito tic activity o f the
neoplastic cells m ay result in a m istaken diagnosis o f sarcom a.24
T he FN A sm ear consists o f fragm ents o f fib ro fa tty tissue studded
w ith sm all ro u n d cells, spindle cells, e p ith e lio id cells, and pleo-
m o rp h ic cells w ith p ro m in e n t n u c le oli in various p rop o rtion s
w ith the cytom orp h olog y between a lip o m a and a sarcom a
(Figs 2 8 .1 4 -2 8 .1 7 ) , depending o n the p ro p o rtio n o f various
com ponents in the aspirate and in d iffe re n t passes fro m the
Fig. 28.14 Angiomyolipoma of the liver. Fragments of stromal tissue
interspersed with fat. FNA smear (Romanowsky x LP).
a
f >
Fig. 28.15 Angiomyolipoma of the liver. Fragments of spindle cells and
epithelioid cells interspersed with fat. FNA smear (Papanicolaou x MP).
same tu m o r.19 Awareness o f the variable cytologic appearances
o f neoplastic cells, the p ositive H M B -45 and s m o o th m uscle
action im m u n o s ta in in g on the cell block, coupled w ith CT scan,
m ay establish the diagnosis.
Key features of hepatic angiomyolipoma
• C T scan: circum scrib ed ro u n d m ass w ith areas o f lo w
a tte n u a tio n c o n siste n t w ith fat.
• S o no g ram : w e ll circum scrib ed , h ig h ly echogenic mass.
• Frag m ents o f fa t-c o n ta in in g m e sen c hym al tissue studded
w ith sp in d le cells and a typ ic al e p ith e lio id cells o f va rio u s
p ro p o rtio n s .
• C o exp re ssion o f m e la n o m a m a rk e r a nd s m o o th m uscle
m arker.
879
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