rminal
aperture be passed along the trachea beyond the seat of obstruction.

#Adenoma of the Thyreoid.#--In this condition the swelling of the
thyreoid is due to the growth within its substance of one or more
adenomas of variable size and surrounded by a capsule. The rest of
the gland may be normal, or may show some degree of hyperplasia. Some
are solid, others undergo cystic degeneration, the glandular tissue
being replaced by a quantity of clear or yellowish fluid, sometimes
mixed with blood. The cysts thus formed may be unilocular or
multilocular, and intra-cystic papillary vegetations frequently grow
from their walls. The walls of the cysts may be thin, soft, and
flaccid, or thick and firm, or they may even be calcified.

The thyreoid is enlarged, but instead of the uniform enlargement which
characterises the parenchymatous goitre, it tends to be uneven, with
hillocky projections corresponding to the individual cysts (Fig. 280),
and in these fluctuation may be detected. It is to be noted that
there are no toxic symptoms in cystic adenoma.

[Illustration: FIG. 280.--Multiple Adenomata of Thyreoid in a woman
aet. 50.

(Mr. D. M. Greig's case.)]

[Illustration: FIG. 281.--Cyst of Left Lobe of Thyreoid.

(Mr. D. M. Greig's case.)]

The treatment is necessarily operative; cystic tumours may be tapped
and injected with iodine, but the more satisfactory procedure, both
with the solid and cystic forms, is to incise freely the overlying
thyreoid tissue and enucleate the tumour.

#Malignant Disease of the Thyreoid.#--This, whether in the form of
_carcinoma_ or _sarcoma_, usually develops in a gland that has been
the seat of goitre for several years, although it may begin in a
previously healthy gland.

_Clinical Features._--Both sexes, above the age of fifty, are affected
in about equal proportion. The characteristic features are that the
tumour undergoes a progressive increase in size, that it becomes fixed
to its surroundings, that its surface tends to be uneven and nodular,
and its consistence densely hard. The voice often becomes hoarse from
abductor paralysis due to infiltration by the growth, usually of the
left recurrent nerve. The effects upon the trachea are more decided
and more progressive than in parenchymatous goitre; it displaces and
compresses the trachea and frequently overlaps it, so as to bury the
air-passage completely. If the tumour tissue has actually penetrated
the trachea, the expectoration