I'm working on/reading a scientific article about the use and effects of Corticosteroid or Ketorolac on rabbit tendons and I got stuck at infiltration in the following excerpts:

"Despite the increased adhesion formation noted grossly, minimal differences in lymphocytic/plasmacytic infiltration, focal histiocytic infiltration were noted between the (...) groups"

"Tendon specimens were analyzed for evidence of necrosis, lymphocytic/plasmacytic inflammatory infiltration, focal histiocytic inflammation, and vascularity."

I found in medical dictionaries that infiltration is " the pathological diffusion or accumulation in a tissue or cells of substances not normal to it" but this definition is similar to neoplasia's (according to The Free Dicitionary, "an abnormal new growth of tissue; abnormal proliferation of benign or malignant cells").

Does someone know if they can be synonyms?

Thank you.

  • From the two definitions you've quoted, it sure doesn't sound like they're synonymous; infiltration seems to carry a sense of a foreign agent, something the definition of neoplasia you quoted appears to lack. – Dan Bron May 2 '15 at 21:03
  • I doubt that most authorities consider them to be synonymous, – Hot Licks May 2 '15 at 21:40
  • This is very dark stuff, Tom. – Edwin Ashworth May 2 '15 at 21:41
  • Thank you so much. I didn't notice the difference. I read as if not normal to it refers to accumulation, not tissue/cells. – Lorena Rocha May 2 '15 at 21:50

I'd say that inflammatory infiltration refers to diffuse appearance of foreign cells, whereas neoplasia refers typically (but not always) to a mass or tumor.


  • I read as if not normal to it refers to accumulation, not tissue/cells, so I didn't notice the difference. Big thanks for the pdf. – Lorena Rocha May 2 '15 at 21:51

Neoplasia and infiltration are definitely not synonyms.

Consider the VINDICATES mnemonic for differential diagnosis: Vascular, Infectious, Neoplastic, Degenerative, Idiopathic, Congenital, Autoimmune, Traumatic, Endocrine, PSychiatric

Neoplasia refers specifically to tumors. From Merriam-Webster: neo·pla·sia \ˌnē-ə-ˈplā-zh(ē-)ə\ noun 1 :the formation of tumors 2 :a tumorous condition

Whereas infiltration can occur in many disease categories. Here's some examples from random articles:

Neoplastic infiltration of the sphenoid wing: a rare manifestation of metastatic colorectal cancer. Pinato DJ, et al. Asia Pac J Clin Oncol. 2011

Metrics of cellular and vascular infiltration of human acellular dermal matrix in ventral hernia repairs. Campbell KT, et al. Plast Reconstr Surg. 2012.

Rift Valley Fever Virus Encephalitis Is Associated with an Ineffective Systemic Immune Response and Activated T Cell Infiltration into the CNS in an Immunocompetent Mouse Model. Dodd KA, et al. PLoS Negl Trop Dis. 2014. (This one is infectious.)

COX inhibition enhances inflammatory immune cell infiltration in UV-irradiated human skin: implications for the treatment of sunburn. Nakamura M, et al. Exp Dermatol. 2015.

Etc. etc. You can even have immune infiltration of a neoplasm: Intratumoral CD8+ Lymphocyte Infiltration as a Prognostic Factor and Its Relationship With Cyclooxygenase 2 Expression and Microsatellite Instability in Endometrial Cancer. Suemori T, et al. Int J Gynecol Cancer. 2015.

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