Endocrine System

A solitary, well-circumscribed, encapsulated nodule is seen.

Follicular adenoma thyroid

Follicular adenoma G

Here is another follicular adenoma that is surrounded by a thin white capsule. It is sometimes difficult to tell a well-differentiated follicular carcinoma from a follicular adenoma. Thus, patients with follicular neoplasms are treated with thyroidectomy just to be on the safe side.

Follicular Adenoma thyroid

Intact fibrous capsule around a follicular adenoma

Well-differentiated follicles resemble normal thyroid parenchyma.

Follicular adenoma thyroid


The tumor is composed of cells with abundant eosinophilic cytoplasm and small regular nuclei.



Most cases are solid, whitish, firm & clearly invasive. The tumor shown exhibits a central area of fibrosis
Papillary ca thyroid central fibrosis

A papillary carcinoma with grossly discernible papillary structures.

Papillary carcinoma thyroid.

Papillary carcinoma: Thyroid

Papillary adenocarcinoma: thyroid. It is a well-differentiated papillary lesion, lying within a cystic space. The fibrous capsule is on the right. The papillae have a core of vascular connective tissue and are covered with cuboidal epithelium.

The papillae are lined by cells with characteristic empty-appearing nuclei, (ground glass or "Orphan Annie eye" nuclei) (C). D, Cells obtained by fine-needle aspiration of a papillary carcinoma. Characteristic intranuclear inclusions are visible in some of the aspirated cells.
Papillary carcinoma nuclear features

Nuclear features of papillary carcinoma: optically clear (ground glass) nuclei

Papillary carcinoma thyroid ground glass nuclei

Psammoma body formation within the stroma of the tumor.

Papillary carcinoma: Thyroid

A few of the glandular lumens contain recognizable colloid.

Follicular carcinoma thyroid.

Minimally invasive follicular carcinoma: Thyroid

Capsular (A) and vascular (B) invasion in minimally invasive follicular carcinoma.
A
B

Note its unencapsulated quality, solid appearance, and yellowish tan color

Medullary carcinoma thyroid

Solid pattern of growth with round & spindle cells associated with deposition of pinkish amyloid.
Medullary carcinoma thyroid

c
Medullary carcinoma
Immunocytochemical positivity for calcitonin. The adjacent nonneoplastic thyroid follicles are negative.

Medullary thyroid carcinoma EM

A 70-year-old Iraqi female presented with a 3-month-history of rapidly enlarging thyroid mass with shortness of breath & dysphagia.
Anaplastic (undifferentiated) carcinoma thyroid

The cancer is entirely replacing the gland and extending into the surrounding skeletal muscle.
Anaplastic (undifferentiated) ca thyroid

Anaplastic carcinoma of the spindle cell type. Tumor grows in diffuse fashion around thyroid follicles. Appearance closely simulates that of soft tissue sarcoma.
Anaplastic (undifferentiated) ca spindle cell type thyroid

Several giant tumor cells with huge hyperchromatic nuclei are present in solid and myxoid background.
Undifferentiated (anaplastic) carcinoma