Intranodal palisaded myofibroblastoma

Intranodal palisaded myofibroblastoma, abbreviated IPM, is a rare tumour that classically presents as an inguinal mass.

General

• Rare ~ 55 cases in the world literature.

Demographics:

• Male:female = 2:1.
• Adults - middle age.

Location:

• Usually inguinal lymph node.
• Reported in retroperitoneum.

Treatment:

• Simple excision; rare recurrences have been reported.

Microscopic

Features:

1. Rim of peripheral lymphoid tissue.
   • Remnant of lymph node.
2. Spindle cells with nuclear palisading - key feature.
3. RBC extravasation/hemorrhage.
4. Amianthoid fibers - blood vessel surrounded by collagen with (fine) peripheral spokes.
   • Paucicellular regions.
5. Intracellular and extracellular fuchsinophilic bodies.
   • Smooth muscle actin +ve.

DDx:

• Schwannoma.

Notes:

• Fuchsinophilic = affinity for the acid dye fuchsin.
  • Image: Fuchsinophilic material (flickr.com) - red.

Images:

• www:
  • IPM (surgicalpathologyatlas.com).
  • Amianthoid fibers (nih.gov).
  • Amianthoid fibers (nih.gov).
  • IPM - several images (upmc.edu).
• WC:
  • IPM - intermed. mag. (WC).
  • IPM - high mag. (WC).

IHC

• SMA +ve.
• Cyclin D1 +ve.

Other:

• S100 -ve
  • Excludes schwannoma.
• GFAP -ve.
• CD34 -ve.
• Desmin -ve
• Ki-67 - low.

See also

• Lymph node pathology.
• Lymph node.