Page 552 - Concise Pathology for Exam Preparation ( PDFDrive )

20 Endocrinology 537

Dermopathy
• Skin overlying shins show scaly thickening and induration (pretibial myxoedema).
• Also seen are pigmented papules or nodules with orange peel texture.

Laboratory Findings
• Elevated free T3, T4 and TSH
• Increased diffuse radioactive iodine uptake

Gross Morphology
• Diffusely enlarged gland weighing more than 80 g
• Gland is smooth and soft with an intact capsule.
• Cut surface shows a soft meaty appearance (resembling muscle).

Microscopy

• Follicles are lined by tall columnar cells showing crowding (‘too many cells’), and have
pale scalloped colloid.
• Hyperplasia of the follicular lining epithelium results in the formation of hyperplastic
papillae or pseudopapillae (papillae without fibrovascular cores).
• Large reactive lymphoid follicles with germinal centres may be present in the interfol-
licular stroma.

Q. Write briefly on the aetiopathogenesis, clinical manifestations
and diagnosis of hypothyroidism.
Ans. Hypothyroidism is a structural or functional derangement that interferes with the
production of adequate level of thyroid hormones.

Causes
Thyroidal
• Insufficient thyroid parenchyma:
• Developmental (thyroid dysgenesis)
• Radiation injury
• Surgical ablation
• Hashimoto thyroiditis
• Interference with thyroid hormone synthesis:
• Idiopathic primary hypothyroidism
• Heritable biosynthetic defects
• Iodine deficiency
• Drugs (lithium, iodides, P-amino salicylic acid)
• Hashimoto thyroiditis
Suprathyroidal
• Pituitary lesions (tumours, radiation damage and surgical removal) reducing TSH
• Hypothalamic lesions that reduce thyrotropin-releasing hormone delivery

Classical Clinical Manifestations
• Cretinism: Hypothyroidism developing in infancy and childhood which is character-
ized by impaired development of the skeletal system and CNS presenting as delayed
milestones, delayed bone maturation, severe mental retardation, short stature, coarse
facial features, protruding tongue and umbilical hernia.

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