CNA.42 recognises a membrane-associated antigen on follicular dendritic reticulum cells (FDRCs), different from those detected by other established anti-FDRC antibodies.
FDRCs in
primary and reactive lymphoid follicles of lymph nodes, tonsils, white pulp of spleen and Peyer's patches
scattered paracortical mononuclear cells
weakly with plasma cells
some mast cells show granular staining
some large cortical thymocytes
pancreatic islet cells
gastric chief cells
acini of salivary glands
myelin sheath and neurogenic tumours (schwannoma, ganglioneuroma, neuroblastoma and ganglioneuroblastoma)
smooth muscle of arterial walls
striated skeletal muscle
some smooth muscle tumours
endothelial cells (membrane staining) and vascular tumours
neoplastic cells in 5% of cases of B cell lymphoma
neoplastic cells in 40% of cases of T cell lymphoma
neoplastic cells in 60% of cases of anaplastic large cell lymphoma (strong membrane staining and Golgi positivity)
in angioimmunoblastic T-cell lymphoma, expanded FDRC networks encase post-capillary venules (the neoplastic cells are negative)
Hodgkin's disease:
nodular lymphocyte predominant; highlights FDRCs but L&H cells are negative
classical Hodgkin's disease; diffuse network of FDRCs and, in 20% of cases, some staining of RS cells
FDRC sarcoma
EBV-positive inflammatory pseudotumours of FDRC origin
carcinomas:
some primary gastrointestinal carcinomas
lesser numbers of primary lung carcinomas
fibrosarcomas
not:
other dendritic cells such as interdigitating/Langerhans' cells
Diagnostic utility
References
Delsol G, New antibodies and new applications of old antibodies in the diagnosis of hematolymphoid neoplasms. In Immunohistochemistry Long Course, Nice, October 18-23, 1998.
©SMUHT/PW Bishop