Appendix

Question 1

LAMN and HAMN

Answer 1

**Low Grade Appendiceal Mucinous Neoplasm **
* Low grade epithelial features
* Absence of infiltrative growth

High Grade Appendiceal Mucinous Neoplasm
* High grade epithelual features
* Absence of infiltrative growth

Micro:
* Flat proliferation of mucinous epithelial cells
* Atrophy of underlying lymphoid tissue
* Crypt loss

Molecular:
* KRAS, loss of 5q
* GNAS –> 50% of cases
* HAMN –> may have TP53 or ATM mutations

IHC:
* CK20+
* CDX2+
* SATB2+
* PAX8-

Prognosis:
* If confined to appendix –> largely considered cured by resection
* Extra-appendiceal acellular mucin considered low risk for recurrence or progression

LAMN –> can cause pseudomyxoma peritonei if ruptures

Question 2

Pseudomyxoma Peritonei

Answer 2

• Clincial term, not histological diagnosis
• Malignant condition

Rupture and intra-abdominal spread of mucinous neoplasms:
* Majority from appendiceal mucinous neoplasm
* Ovarian mature teratomas (less common)

Grade:
G1 –> low grade
G2 –> High grade
G3 –> High grade with signet ring cells

• Histologic grade of peritoneal diease is an important prognostic factor

Treatment:

• HIPEC for low grade disease
• Systemic chemo for high grade

Question 3

Goblet Cell AdenoCa

Answer 3

• Often found incidentally
• Most often in distal appendix
• Prognosis –> grade and stage of adenoCa

IHC:
* CK7, CK20 +ve - strong and diffuse
* SATB2 +
* CDX2 +
* CEA +
* Synaptophysin/Chromogranin: Focal or scattered (85-100%)
* Mucicarmine

• Ki67: Variable (0-80%)