PA6.1 | Neoplasia — Definitions, Nomenclature & Characteristics — Summary & Reflection

REFLECT

You have just reviewed the entire framework for tumour classification and behaviour. Before moving on, take 3 minutes to answer these questions in your own words (no notes):

1. You see a histopathology report that reads: 'Poorly differentiated carcinoma with frequent abnormal mitoses, lymphovascular invasion, and metastasis to axillary lymph nodes.' List every malignant feature named in this report — and which of the four characteristics each belongs to.

1. A colleague asks: 'Why is melanoma named with '-oma' if it's malignant?' Give a 2-sentence answer.

1. A 55-year-old woman has a 'fibroma' of the uterus (leiomyoma). What can you tell her about its likely behaviour, based on what you've learned today?

KEY TAKEAWAYS

Key takeaways from this module:

• Neoplasia (Willis): autonomous, persistent, uncoordinated growth — two components: parenchyma (neoplastic cells) + stroma (desmoplasia, vessels)

• Nomenclature: benign = tissue + -oma; malignant epithelial = carcinoma; malignant mesenchymal = sarcoma; primitive = -blastoma; haematological = leukaemia/lymphoma

• Critical exceptions (malignant with -oma): Melanoma, Lymphoma, Seminoma, Mesothelioma, Hepatoma, Glioma

• Special categories: Teratoma (all 3 germ layers); Hamartoma (native tissue, disorganised, not neoplastic); Choristoma (normal tissue, ectopic location)

• Four characteristics — benign vs malignant: differentiation/anaplasia → rate of growth → local invasion → metastasis (the only absolute criterion)

• Anaplasia: pleomorphism + ↑ N:C ratio + hyperchromasia + prominent nucleoli + atypical mitoses + loss of polarity + tumour giant cells

• Metastatic routes: lymphatic (carcinomas) → haematogenous (sarcomas; liver/lung commonest) → transcoelomic (body cavities)

• CIS vs invasive: basement membrane intact = CIS (curable); basement membrane breached = invasive carcinoma (metastatic risk)