PART TWO
Diagnostic Cytology
Fig. 23.4 Diffuse colloidal hyperplasia. (A) Monolayer tissue fragment of follicular cells with honeycomb pattern set in a background of abundant different-
sized, irregular-folded colloid (May-Grunwald-Giemsa x HP). (B) Cracked colloid forming mosaic pattern (May-Grunwald-Giemsa x HP). (C) Balls of dense
inspissated colloid (May-Grunwald-Giemsa x HP).
Diffuse Colloidal Hyperplasia
This is the most common form of thyroid goiter in adolescent
and young women. It represents part of the initial response of
the thyroid to a peripheral thyroxine deficit. The gland is dif-
fusely enlarged and composed of the distended follicles, lined
by flat epithelium, with abundant pale colloid. Focally, small
active follicles protrude into adjacent follicles, corresponding to
areas of active hormonal synthesis (Sanderson polster).24,64
Key features of diffuse colloidal hyperplasia
• Abundant amber-colored colloid; and
• Scanty follicular cells dispersed or forming loose mono-
layers or distended follicles with smooth contour.
In some cases, there are no differences with aspirates from
the normal thyroid gland. In the goiter, the colloid is more
abundant and can be mixed with blood or form a protein film
with folds or a mosaic-like crackling (Figs 23.4A and 23.4B);
less often, it appears as dense spherical clusters (Fig. 23.4C). The
follicular cells may have a normal appearance or a vacuolated
cytoplasm. From a practical point of view, the combination
of a discretely enlarged gland with a smear rich in colloid and
follicular cells of normal appearance is suggestive of colloidal
goiter. Although aspirates with abundant colloidal material are
indicative of a benign lesion, some papillary and follicular carci-
nomas also contain abundant colloid. C cells are rarely observed
in a smear from a normal or hyperplastic thyroid gland, but
when they exist, their morphology is similar to that of the cells
of a medullary carcinoma.106
Nodular Hyperplasia
This is the most common disorder of the thyroid gland. It
may be sporadic or endemic. It is characterized by progressive
enlargement of the thyroid gland in response to repeated cycles
of thyroid stimulation and involution. The thyroid gland is
asymmetrically enlarged and contains poorly delimited nodules
of different sizes and heterogeneous architecture and cytology.
The nodules may be single (solitary nodule), but usually they
are multiple. Most nodules are nonfunctioning (cold nodules).
Functional nodules (hot nodules) are accompanied by a euthy-
roid clinical picture in 80% of cases; only 20% of cases exhibit
hyperthyroidism
(toxic
nodular hyperplasia).24,64 Although
the low incidence of malignancy reported in hot nodules may
642
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