Acute thyroiditis is usually caused by an infection and is associated with pharyngitis, tonsillitis, or other infections. Common causative agents include bacteria like Streptococcus and Staphylococcus, as well as some fungi and viruses. Acute thyroiditis presents with neutrophilic infiltration and tissue necrosis in the thyroid. Granulomatous thyroiditis, also known as De Quervain's thyroiditis, typically affects middle-aged women and presents with sore throat, painful swallowing, and thyroid tenderness. Microscopy shows granulomas surrounding thyroid follicles. Lymphocytic thyroiditis, including Hashimoto's thyroiditis, is an autoimmune condition characterized by lymphocytic infiltration of

1. THYROIDITIS
Dr. SOBIA KHALID

3. • Acute thyroiditis is usually of infectious nature.
• ASSOCIATED with
– Pharyngitis
– Tonsillitis
– generalized sepsis
– major trauma to the neck with an open wound.
– malnourished infant
– the debilitated elderly
– the immunocompromised patient.

4. CAUSATIVE AGENTS
• Streptococcus haemolyticus
• Staphylococcus aureus
• Pneumococcus
• gram-negative bacteria
• fungi (particularly Candida)
• Pneumocystis
• Viral infection is rare e,g cytomegalovirus
infection of the thyroid in patients with AIDS.

5. MORPHOLOGY
• NEUTROPHILIC INFILTRATION
• TISSUE NECROSIS
• Nonsuppurative and suppurative forms exist,
the latter sometimes evolving into an abscess.
• The interesting observation has been made
that a large number of cases of recurrent
acute suppurative thyroiditis (especially when
left-sided) are secondary to the presence of a
piriform sinus fistula.

6. DIAGNOSIS & TREATMENT
• Fine needle biopsy with smear cytologic
examination and cultures.
• For pyriform sinus fistula....barium meal
• Rx is fistulectomy.
• Medical Rx of acute thyroiditis is usually
effective, but abscesses need to be drained
surgically.

7. Granulomatous (de quervain) thyroiditis
Palpation thyroiditis
Tuberculosis
Sarcoidosis
Mycoses
Postoperative necrotizing granulomas

9. GRANULOMATOUS THYROIDITIS, AKA
DE QUERVAIN OR SUBACUTE
THYROIDITIS
• TYPICALLY PRESENTATION
 INITIALLY
– middle-aged women
– sore throat
– painful deglutition
– marked tenderness on palpation in the thyroid region
– often associated with fever and malaise
 LATER ON
– pressure symptoms
– mild hypothyroidism
– majority of cases there is complete resolution
– sometimes asymmetric involvement of the gland can mimic
carcinoma.

10. HORMONE STATUS
• Elevated serum levels of T4 and T3 in
combination with complete suppression of 131I
uptake are typical of the initial phase of this
disease, which has been found to be
associated with the HLA-B35 haplotype.

11. GROSS
• EARLIER
– involves the entire gland
– enlargement is often asymmetric
– approximately twice its normal size
• LATER ON
– the involved areas are firm
– In contrast to Riedel thyroiditis, there is usually
little or no adherence to the surrounding
structures.

12. MICROSCOPY
• Areas of marked inflammation
and granulomas containing
foreign body giant cells are
present.
• It is characteristic for these
granulomas to surround
follicles and for the
multinucleated giant cells
(most of which are of
histiocytic nature) to engulf
colloid
• The granulomas are not very
distinct, and caseation necrosis
is consistently absent.
• Areas of fibrosis are also seen,
usually in a patchy distribution.
• Different stages of the same
process may be seen in the
same gland.

14. Granulomatous thyroiditis showing multiple granulomas centered in thyroid follicles

15. • There is positivity for in the center of the
granuloma is a feature of the acute stage.
• Strong immunoreactivity for is found in
the late stage of the disease.
• The etiology is unknown.
• Although the disease often follows an infection of
the upper aerodigestive tract, but the thyroiditis
itself is of nonbacterial nature.
• A viral etiology has been often suggested on
clinical and epidemiologic grounds but not
conclusively proved.

17. AKA MULTIFOCAL GRANULOMATOUS
FOLLICULITIS
• TERM is used for a relatively common, clinically
insignificant, and grossly inconspicuous thyroid process in
which collections of histiocytes (some of them foamy),
lymphocytes, and a few multinucleated giant cells are seen
within the lumen of scattered thyroid follicles.
• In some of these follicles, the inflammatory infiltrate
disrupts the epithelium and extends into the perifollicular
region.
• It seems to be the result of minor trauma to the gland,
sometimes spontaneous and sometimes thought to be
induced by vigorous palpation on physical examination,
hence the term palpation thyroiditis.

18. “Palpation thyroiditis” in a thyroid removed for papillary thyroid carcinoma. This form
of thyroiditis is characterized by the presence of histiocytes and lymphocytes, is
usually focal, and is associated with minor trauma to the gland.

20. • as a primary cases are rare.
• In disseminated miliary tuberculosis, it is
common for an occasional tubercle to occur
within the gland.
• It is also possible for tuberculosis of cervical
lymph nodes or larynx to involve the thyroid
gland secondarily.
• Many of the cases diagnosed in the past as
tuberculosis of the thyroid were actually
examples of granulomatous (de Quervain)
thyroiditis.

22. • It may involve the thyroid in the form of
interstitial (rather than follicle-centered)
noncaseating granulomas in patients with
systemic disease.
• Occasionally it manifests initially as a thyroid
mass.

24. • Mycoses of various types have been
described, most of them occurring in
immunocompromised hosts.
• In many of these cases, the tissue changes are
characterized by necrosis and acute
inflammation rather than granuloma
formation.

26. • Postoperative necrotizing granulomas,
vaguely simulating rheumatoid nodules and
morphologically similar to those more
commonly seen in the prostate and bladder,
have been observed within the thyroid.

27. Lymphocytic thyroiditis
 Hashimoto thyroiditis

28. • Autoimmune thyroiditis is characterized
functionally by the production of
autoantibodies that alter thyroid function.
• Autoimmune thyroid disease.
• Autoimmune thyroiditis and Grave’s
disease........ hashitoxicosis.
• There is an immune-mediated insult that leads
initially to diffuse or nodular hyperactivity of
the gland and eventually to exhaustion
atrophy, manifested by diffuse oxyphilia of the
follicular epithelium.

29. MECHANISMS LEADING TO
AUTOIMMUNE THYROIDITIS
• The mechanisms leading to autoimmune thyroiditis are
of both humoral and cellular nature.
• Circulating autoantibodies exist against thyroglobulin
and other follicular cell antigens, notably thyrotropin
(TSH) receptors (TSHR).
• However, it has been suggested that the initial factor
resulting in autoimmune thyroiditis is an organ-specific
defect in suppressor T lymphocytes.
• No convincing role of aberrant HLA-DR antigen
expression.

30. Morphology
• Common denominator of autoimmune thyroid
disease is the presence of extensive lymphocytic
infiltration of the gland associated with germinal
center formation.
• Grave’s disease when the follicles are diffusely
hyperplastic,
• Lymphocytic thyroiditis when they are relatively
normal.
• Hashimoto thyroiditis when they are lined by
follicular cells showing extensive oncocytic
change.

31. Features Lymphocytic thyroiditis Hashimoto’s thyroiditis Reidel’s thyroiditis
AKA juvenile form’ of
lymphocytic/autoimmun
e thyroiditis
struma lymphomatosa riedel struma, fibrous
thyroiditis, and
invasive thyroiditis
Age Children women over 40 years of
age
adult and elderly
patients, slight
predilection for
females
Autoimmune
process
+ + -
Clinical features asymptomatic diffuse
goiter, can be
Preceded by Acute
inflammatory process
and tenderness.
AI + T, diffuse firm
thyroid enlargement,
sometimes
accompanied by signs
of tracheal or
esophageal
compression.
AI+T, Ill-defined thyroid
enlargement,
profound dyspnea.
extremely firm.
binds the soft tissues
of the neck in an iron
collar .
May compress the
trachea to a slitlike
state.

32. Features Lymphocytic
thyroiditis
Hashimoto’s
thyroiditis
Reidel’s thyroiditis
Hormone status Initially mild
hyperthyroidism,
later hypothyroidism
Radioactive iodine
uptake
Low than Grave’s
disease
During surgery the thyroid gland is
easily separated from
other structures. The
facial attachment
between the thyroid
gland and the
tracheal wall is, at
times, slightly
thickened, but there
is no strong fixation
the thyroid gland is
not easily separated
from other
structures. The facial
attachment between
the thyroid gland and
the tracheal wall
thickened and
strongly fixed.

33. GROSS Lymphocytic thyroiditis Hashimoto’s thyroiditis Reidel’s thyroiditis
The gland is diffusely
enlarged and of increased
consistency.
diffuse and symmetrical
enlargement of the gland.
distinctly multinodular.
Consistency is firm but
not stony hard. No
extension of the process
outside the gland.
Process is asymmetric .
It involves only localized
areas of the thyroid gland.
The affected portion is
stony hard and cuts with
great resistance.
Dense fibrous tracts
extend from the thyroid
capsule into adjacent
muscle so that at surgery
the tissue planes are
obliterated.
Cut
surface
There is a solid, white,
vaguely nodular cut
surface
The cut surface is friable,
vaguely or distinctly
nodular, yellowish gray,
and greatly resembles a
hyperplastic lymph node.
Colloid is not clearly
discernible. Necrosis and
calcification are absent.
On cross section, areas
with complete
obliteration of the
architecture alternate
with others having a
nearly normal
appearance.

34. Cut surface of thyroid involved by Hashimoto thyroiditis. The appearance is reminiscent of a
hyperplastic lymph node.

35. Reidel’s thyroiditis

36. Microscopy Lymphocytic
thyroiditis
Hashimoto’s
thyroiditis
Reidel’s thyroiditis
Interstitium Lymphocytic
nodules with
germinal centers
are seen scattered
in the interstitium.
lymphocytic
infiltration of the
stroma. The lymphoid
tissue is distributed
within and around
the lobules, and it
invariably exhibits
large follicles with
prominent germinal
centers. Lymphocytes
predominate, T cells
predominating over B
cells.
The fibrous tissue that is
frequently extensively
hyalinized completely
replaces the area of the
gland involved.
Skeletal muscle cells in
the immediate area are
often directly infiltrated
by this connective tissue.
Giant cells are absent.
The inflammation
present is patchy and of
mononuclear type, with
a predominance of
lymphocytes and plasma
cells.
Follicles The follicles are
generally
unremarkable, but
some may show
atrophy and/or
oncocytic change.
oxyphilic change of
the follicular
epithelium.
Plasma cells,
histiocytes, and
scattered
intrafollicular
multinucleated giant
cells can be present.

37. Features Lymphocytic
thyroiditis
Hashimoto’s
thyroiditis
Reidel’s thyroiditis
Blood vessels Collections of
eosinophils may
also be present.
Medium-sized veins
encased by the
fibrosis may show
inflammation of
their wall, an
important
diagnostic feature.

38. Lymphocytic thyroiditis

41. • An oncocyte is an epithelial cell characterized by
an excessive amount of mitochondria, resulting in
an abundant acidophilic, granular cytoplasm.
Oncocytes can be benign or can
undergo malignant transformation.
• Also known as:
• Hürthle cell (thyroid gland only)
• Oxyphilic cell,
• Askanazy cell,
• Apocrine metaplasia (breast gland only).

42. ONCOCYTES

43. • Immunohistochemically, the follicular cells of
autoimmune thyroiditis show greater reactivity
for keratin (particularly the high molecular weight
types), S-100 protein, HLA-DR, and N-acetyl-a-D-
galactosamine than the corresponding normal
cells, their immunohistochemical profile thus
resembling that of the cells of papillary
carcinoma.
• Biochemically, the oncocytic cells of Hashimoto
thyroiditis have defects of cytochrome-c oxidase
and deletions of mitochondrial DNA.

44. Hashimoto thyroiditis showing lymphoid follicles with prominent germinal
centers and oncocytic follicular epithelium.

45. Hashimoto thyroiditis with extensive fibrosis, atrophy of follicular
epithelium, and squamous metaplasia

46. Riedel thyroiditis showing sclerosis, chronic inflammation, and parenchymal
atrophy.

47. Reidel’s thyroiditis

48. Inflammation of a vein in Riedel thyroiditis.

50. • It represents instead a manifestation of the
group of idiopathic disorders generically
known as inflammatory fibrosclerosis. As such,
it may be seen coexisting with mediastinal or
retroperitoneal fibrosis, sclerosing cholangitis,
or inflammatory pseudotumor of the orbit.
• The increased number of IgG4-positive plasma
cells common to these disorders can be a
useful clue to the diagnosis, since IgG4 is an
otherwise rare IgG idiotype.

51. • (Painless) silent thyroiditis is a transient form
of hyperthyroidism characterized by a
painless, nontender thyroid gland showing
initially the features of hyperplasia followed
by focal lymphocytic thyroiditis. It is believed
that postpartum thyroiditis is a
pathogenetically related process with a similar
sequence of morphologic events.

53. • It is characterized by multiple (sometimes
innumerable) foci of fibrosis throughout the gland,
often having a radial configuration.
• On low power, the appearance can be indistinguishable
from that of papillary microcarcinoma, but on high
power one appreciates the lack of a neoplastic
glandular component.
• There are instead entrapped follicles in the midst of the
scar, often distorted and lined by cells with vesicular
(but not optically clear) nuclei (with so-called reactive
atypia).
• Sometimes there is also a florid hyperplastic change in
the follicles located at the interphase between the
fibrotic strands and the surrounding parenchyma.
• On occasion, one or two of these star-like fibrotic foci
are seen to contain a minute papillary carcinoma.

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