thyroid neoplasm is the major causes in certain country especially those are underdeveloped

1. FRONT E
I R
Lecture 5. Diffuse & Multiple
nodular Thyroiditis & Thyroid
Neoplastic:

2. • Most common thyroid disease is an enlargement of
the thyroid, or goiter.
• This type of thyroiditis result from Diffuse and
multinodular goiters are the result of impaired
synthesis of thyroid hormone.
• Cause:
• Dietary iodine deficiency.
• Pathogenesis:
1. Endemic goiter occurs in geographic areas where
the diet contains little iodine. common in
mountainous areas of the world.
2. Sporadic goiter when there is an increased
physiologic demand for T4. caused by
goiterogenous substance or enzyme defect.

5. • Morphology:
oDiffuse goiter:
• TSH-induced hypertrophy and hyperplasia of
thyroid follicular cells usually result in diffuse,
symmetric enlargement of the gland.
oColloid goiter:
• The follicular epithelium involutes to form an
enlarged, colloid-rich gland.
oMultinodular goiter:
• multilobulate, asymmetrically enlarged glands
caused by recurrent episodes of hyperplasia and
involution.

6. • Clinical Features:
1. A large neck mass.
2. Airway obstruction.
3. Dysphagia.
4. Compression of large vessels in the neck and
upper thorax (so-called “superior vena cava
syndrome”).
5. Toxic multinodular goiter or plummer syndrome
_ thyrotoxicosis.
6. Tendency to form malignancy in long-standing
multinodular goiters.

7. (A) Gross morphologic appearance. The coarsely nodular gland contains areas of
fibrosis and cystic change. (B) Photomicrograph of a specimen from a
hyperplastic nodule, with compressed residual thyroid parenchyma on
the periphery. The hyperplastic follicles contain abundant
pink “colloid” within their lumina. Note the absence of a prominent
capsule

9. Adenomas:
• Adenomas of the thyroid are benign neoplasms
derived from follicular epithelium.
• Pathogenesis:
• Driver mutations in the TSH receptor signaling
pathway play an important role in the pathogenesis
of toxic adenomas.
• Morphology:
• Is a solitary.
• well-defined, intact capsule.

10. Follicular adenoma of the thyroid gland. (A) A solitary,
wellcircumscribed nodule is visible in this gross specimen. (B) The
photomicrograph shows well-differentiated follicles resembling those of
normal thyroid parenchyma.

12. • Clinical feature:
1. Painless nodules.
2. Difficulty in swallowing.
3. Feature of thyrotoxicosis if toxic adenomas.
• Diagnosis:
• Injection of radioactive iodine, most adenomas take up
iodine less avidly than normal thyroid parenchyma.
• Cold nodule _ leads malignancy.
• Hot nodule.
• Ultrasonography and fine needle aspiration biopsy.
• Treatment:
• Removed surgically.
• Thyroid adenomas carry an excellent prognosis and do
not recur or metastasize.

13. Carcinomas:
• Mild aged female.
• Most thyroid carcinomas (except medullary
carcinomas) are derived from the thyroid follicular
epithelium.
• The major subtypes of thyroid carcinoma and their
relative frequencies are as follows:
A. Papillary carcinoma (accounting for more than 85%
of cases).
B. Follicular carcinoma (5% to 15% of cases).
C. Anaplastic (undifferentiated) carcinoma (<5% of
cases).
D. Medullary carcinoma (5% of cases).

14. • Pathogenesis:
• Distinct molecular events are involved in the
pathogenesis of the four major variants of thyroid
cancer.
1. Genetic alterations in the three follicular cell–derived
malignancies are clustered along two oncogenic
pathways that lie downstream of growth factor
receptors and RAS—the mitogen-activated protein
(MAP) kinase pathway and the phosphatidylinositol-
3-kinase (PI-3K)/AKT pathway.
2. Environmental Factors. The major risk factor
predisposing to thyroid cancer is exposure to ionizing
radiation, particularly during the first 2 decades of
life.

16. A_ Papillary Carcinoma:
• Most common form of thyroid cancer.
• It occurs in any age.
• Previous exposure to ionizing radiation.
• Morphology:
• Macroscopically_
Solitary or multifocal lesions.
Some are well defined others are ill defined.

17. • Microscopically_
 Branching papillae.
 Orphan Annie eye nuclei ‘best in Diagnosis’.
 Psammoma bodies ‘Concentrically calcified structures’.
 Foci of lymphatic invasion by tumor are often present.
Orphan Annie eye nuclei

19. • Clinical Features:
• Painless mass in the neck.
• Treatment:
Surgical resection.
Radioactive iodine therapy 4-6week after surgery.
• Prognosis with 95% 10 year survival.
Psammoma bodies, These structures
are almost never found in follicular
and medullary carcinomas.

20. B_ Follicular Carcinoma:
• They are more common in women (occurring in a ratio
of 3: 1).
• Manifest at an middle or older age.
• more frequent in areas with dietary iodine deficiency.
• while its incidence has either decreased or remained
stable in iodine-sufficient areas of the world.
• Morphology:
• While its incidence has either decreased or remained
stable in iodine-sufficient areas of the world.
• Hürthle cell variants.

21. • Metastatic to the lung, bone and liver.
• Clinical feature:
1. Solitary cold thyroid nodules.
2. Irregular firm
• Treatment:
• Surgical resection.
• The prognosis 0-year survival rate is 50-70%.

24. C_ Anaplastic Carcinoma:
• These are undifferentiated tumors.
• Clinical Features:
• Anaplastic carcinomas grow with wild abandon
despite therapy.
• Metastases to distant sites are common.
• Death occurs in less than 1 year as a result of
aggressive local growth and compromise of vital
structures in the neck.

26. D_ Medullary Carcinoma:
• Neuroendocrine tumors derived from the parafollicular
cells, or C cells.
• Medullary carcinomas arise sporadically in about 70%
of cases.
• The remaining 30% are familial.
• Medullary carcinomas are associated with or without
multiple endocrine neoplasia (MEN) syndrome.
• Calcitonin lowers serum calcium by increasing renal
calcium excretion but is inactive at normal physiologic
levels.
• High levels of calcitonin produced by tumor may lead to
hypocalcemia.

28. • Calcitonin often deposits within the tumor as
amyloid.
• Biopsy reveals sheets of malignant cells in an
amyloid stroma.
• Treatment:
• Detection of the mutation warrants prophylactic
thyroidectomy.