PART TWO
Diagnostic Cytology
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Fig. 26.15 Precursor T-lymphoblastic lymphoma. (A) A monotonous population of widely dispersed small to medium-sized lymphoid cells is seen. Direct
smear of fine-needle aspirate (Papanicolaou x MP). (B) Widely dispersed small to medium-sized immature lymphoid cells with focal nuclear convolutions
(arrow) are present. Mitotic figures are easily identified here. Direct smear of fine-needle aspirate (Papanicolaou x OI). (C) There are mitotically active small
lymphoid cells containing round hyperchromatic nuclei and scanty cytoplasm (left). The lymphoma cells show nuclear staining for terminal deoxynucleotidyl
transferase (TdT) (right). Histologic sections of surgical specimen (H&E and immunostain for TdT x MP and MP, respectively).
elsewhere m ay also secondarily in vo lve lym p h nodes in the
m ed iastinum .
Fine-needle asp iration o f p rim a ry m ed iastinal large B-cell
lym p h o m a often yields a m o n o to n o u s p o p u la tio n o f w id e ly dis-
persed large atypical ly m p h o id cells w ith h ig h m ito tic and apop-
to tic activities (Fig. 26.1 6 B ).5 Focal cellular aggregates m ay be
evident, m im ic k in g e p ith elial tum ors. L ym p h og lan d ular bodies
(b asop hilic cytoplasm ic fragm ents o f ly m p h o id cells), b u t n o t
"tig ro id " appearance, are c o m m o n ly seen in th e background.95,96
It is n o te w o rth y th a t the presence o f lym p h o g la n d u la r bodies
is ind icative o f a ly m p h o id lesio n b u t does n o t denote m alig -
n a n t ly m p h o id p ro life ra tio n . H ig h-p ow er e xa m in ation reveals
m ed ium -sized to large "c e n tro b la st-like " cells w ith focal nuclear
m em brane irregularities, ro u n d nuclei, vesicular c hro m a tin pat-
tern, and several sm all peripherally-located b asop hilic nucle-
o li (Fig. 26.16C ). M u ltilo b a te d fo rm s are id en tifie d in som e
examples.97 Occasional cases w ith m ore p leo m o rp hic nuclei
and ab und ant a m p h o p h ilic cytoplasm are present, resem bling
the "R eed -S ternb erg -like" cells o f H od g kin's lym p h om a. H odg-
kin's lym p h o m a , however, does n o t show a predom inance o f
large-cell p o p u la tio n in cytologic preparations. In general, the
lym p h o m a cells are at least three tim es the diam eter o f a n o rm a l
lym phocyte. The sclerotic strom a m ay be appreciated in the cell
b loc k sections. However, the fib rous m a trix som etim es causes
cellular d isto rtio n , resulting in an elongated o r a sp in d ly appear-
ance o f the lym p h o m a cells.39,53,96,98
T he diagnosis o f lym p h o m a can be confirm ed b y im m u n o -
cytochem ical study o r flo w cytom etry. F lo w c ytom etry is a use-
fu l adjunctive investig ation in diagnosis o f even som e rare types
o f lym p h o m a .99 Typically, th e lym p h o m a cells d iffu se ly express
B-cell m arkers (e.g. C D 20 and C D 79a). C D 23 p o s itiv ity is u su ally
dem onstrated. Focal w eak sta in in g fo r C D 30 m ay also be noted.
792
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