5. Neoplasms Flashcards
Types of neoplasms
- Benign thyroid neoplasm
- Follicular adenoma & Hurthle cell adenoma - Thyroid carcinoma
- Follicular
- Papillary
- Anaplastic
- Medullary - Thyroid lymphoma
Benign thyroid neoplasms
Follicular adenoma & Hurthle cell adenoma
Morphology of follicular & hurthle cell ademona
- [Grossly]
- Rounded, encapsulated, well demarcated nodule
- Cut surface: regions of hemorrhage, cystic change & variable colour (red-brown if high colloid content; grey-white if high cellularity; orange brown if Hurthle cell change) - [Histologically]
- Thyroid follicles (mixed macro& microfollicles) within tumour substance
- Completely surrounded by an intact fibrous capsule which demarcates tumour from normal atrophic parenchyma (main distinguishing feature from multinodular goitre)
- May exhibit Hurthle cell change (Hurthle cell adenoma)
Clinical Features of benign thyroid neoplasms
- Solitary painless nodule
- Laboratory tests
- Typically euthyroid
- Typically no increased radioiodine uptake - Differential diagnoses for follicular adenoma
- Dominant nodule in multinodular goitre
i. Multinodular goitre will not have a capsule & will have multiple other nodules in the background
- Follicular carcinoma
i. Follicular carcinoma will have capsular or vascular invasion
ii. Need to assess entire capsule via extensive histologic sampling of tumour-capsule-thyroid interface to make definite diagnosis (hence highlighting limitations of fine needle aspiration & frozen section assessment) - Papillary carcinoma (follicular variant)
i. Papillary carcinoma will have diagnostic nuclear features
Cell of origin for follicular carcinoma
Follicular cell
Frequency of follicular carcinoma
75-80%
Age of diagnosis for follicular carcinoma
Mean 40
Prognosis for follicular carcinoma
Good
Genetic aberrations for follicular carcinoma
RAS, t(2;3)
Morphology of follicular carcinoma
- [Grossly]
- Minimally invasive: well-defined, hard to find capsular invasion
- Widely invasive: obvious, extensive capsular or extrathyroidal extension
- Typically solitary - [Histologically]
- Similar to follicular adenoma EXCEPT that it has evidence of capsular/vascular invasion
- May have Hurthle cell change (Hurthle cell carcinoma)
Clinical features of Follicular carcinoma
- Slow growing painless nodule (typically solitary)
- Little propensity for lymphatic spread, vascular spread common
- Prognosis: (depends on degree of invasion)
- Minimally invasive: 10-year survival > 90%
- Widely invasive: 10-year survival = 50-70%
Cell of origin for papillary carcinoma
Follicular cell
Frequency of papillary carcinoma
10-20%
Prognosis for papillary carcinoma
Good
Genetic aberrations for papillary carcinoma
RET (RET/PTC rearrangements), BRAF
Morphology of papillary carcinoma
- [Grossly]
- May be solitary or mutilfocal
- Ranges from being encapsulated to infiltrative
- Whitish nodules, cystic change, calcifications & fibrosis
- Cut surface may reveal macroscopic papillary foci - [Histologically]
- Diagnostic nuclear features (present in all types of PTC):
i. Orphan Annie Eye nuclei (optically clear/empty looking due to finely dispersed chromatin)
ii. Nuclear grooves & pseudoinclusions (due to cytoplasmic invaginations)
- Classical PTC
i. Well formed papillae with fibrovascular cores
ii. Cuboidal uniform cells
iii. Psammoma bodies (concentrically calcified bodies within papillae cores)
iv. Fibrosis, calcifications
v. Lymphatic invasion - Follicular variant
i. Follicular architecture
ii. Note: need to distinguish from follicular adenoma & carcinoma (by using diagnostic papillary carcinoma nuclear features) - Encapsulated variant
i. Encapsulated - Tall cell variant
i. Tall columnar cells with intensely eosinophilic cytoplasm lining papillae - Papillary microcarcinoma
i. Otherwise classical PTC <1cm
Clinical features of papillary carcinoma
- Diagnosed based on nuclear features
- Slow growing painless nodule (may be multifocal)
- Little propensity for vascular spread, lymphatic spread common
- Prognosis: (depends on age, extrathyroidal extension & distant metastases)
- Generally good prognosis
- Worse prognosis when associated with hoarseness, cough & dysphagia
- Histological type (encapsulated variant has excellent prognosis; tall cell variant tends to be more aggressive)
Age of diagnosis of papillary carcinoma
40-50 years old
Cell of origin of anaplastic carcinoma
Follicular cell
Frequency of anaplastic carcinoma
<5%
Age of diagnosis of anaplastic carcinoma
40-50 years old
Prognosis of anaplastic carcinoma
Dismal
Genetic aberrations for anaplastic carcinoma
p53
Morphology of anaplastic carcinoma
- Giant tumour cells (osteoclast-like)
- Spindle cells (sarcomatoid features)
- Small anaplastic cells
Clinical features of anaplastic carcinoma
- Rapidly enlarging bulky mass in the neck
- Compressive symptoms (hoarseness, dyspnea, dysphagia)
- Often spreads beyond thyroid gland with metastases to lung
- Prognosis:
- Dismal, survival in months
Cell of origin of medullary carcinoma
Parafollicular cell
Frequency of medullary carcinoma
5%
Age of diagnosis of medullary carcinoma
Elderly
Prognosis of medullary carcinoma
Variable
Genetic aberrations for medullary carcinoma
RET (associated with MEN II)
Features of medullary carcinoma
- Neuroendocrine tumour (derived from parafollicular cells of thyroid)
- 80% sporadic, 20% familial (either part of MEN II syndromes or familial medullary thyroid carcinoma)
- Sporadic: localized to one lobe, no background of parafollicular cell hyperplasia, occurs in 5th to 6th decade of life
- Familial: multinodular & affects both lobes, background of parafollicular cell hyperplasia, occurs in 2nd decade of life
Morphology of medullary carcinoma
- [Grossly]
- Firm, pale-grey to tan
- Infiltrative edges
- Necrosis & hemorrhage
- Extrathyroidal extension - [Histologically]
- Cells with variable appearance
- Variable architecture (nests, trabeculae, follicles)
- Background of amyloid (deposits of altered calcitonin, shown with Congo Red stain)
- Parafollicular cell hyperplasia in normal surrounding parenchyma (seen mainly in familial tumours)
Clinical features of medullary carcinoma
- Compressive symptoms (dysphagia, hoarseness)
- Paraneoplastic syndrome (VIP causing diarrhea, ACTH causing Cushing syndrome)
- Raised serum calcitonin (but with no significant hypocalcemia)
- Look out for other related tumours to determine if it is part of a MEN II syndrome (adrenals, parathyroid)
- Prognosis: (depends on degree of invasion)
- Sporadic worse than familial
Definition of thyroid lymphoma
Extranodal marginal zone B-cell lymphoma, typically occurring in the setting of Hashimoto thyroiditis; may transform into diffuse large B-cell lymphoma
