Testis & paratestis
Nonneoplastic lesions
Inflammatory pseudotumor
Author: Sean R. Williamson, M.D.
Last author update: 1 December 2012
Last staff update: 22 April 2024 (update in progress)
Copyright: 2002-2024, PathologyOutlines.com, Inc.
PubMed Search: Paratesticular fibrous pseudotumor
Table of Contents
Definition / general | Case reports | Treatment | Gross description | Microscopic (histologic) description | Positive stains | Negative stains | Differential diagnosisCite this page: Williamson S. Inflammatory pseudotumor. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/testisinflammatorypseudtumor.html. Accessed April 23rd, 2024.
Definition / general
- Synonyms: chronic proliferative periorchitis, inflammatory pseudotumor, nodular and diffuse fibrous proliferation, paratesticular fibrous pseudotumor
- Ages 7 - 95 years, peaks in 20's
- Reactive fibrous mass, usually between testicular tunica layers; also involves epididymis and spermatic cord, associated with hydrocele, infection, trauma (Am J Surg Pathol 2010;34:569)
- Some cases may be type of IgG4 associated sclerosing disease (Virchows Arch 2011;458:109, Hum Pathol 2012;43:2084)
Case reports
- 22 year old man with collagen rich stromal tumor attached to testicular tunica albuginea (Hum Pathol 1990;21:866)
Treatment
- Excision
Gross description
- Multinodular thickening of peritesticular tissue or discrete mass of firm white tissue up to 15 cm
- May be an associated hydrocele or hematocele
Microscopic (histologic) description
- Dense fibrous tissue, fibroblasts, inflammatory cells, dystrophic calcification
- With time, cellularity decreases and fibrosis increases
- Usually no necrosis, no pleomorphism, no / rare mitotic activity (Am J Surg Pathol 2010;34:569)
Positive stains
- Smooth muscle actin (myofibroblasts); variable keratin
Negative stains
- Usually ALK1-, suggesting it is unrelated to inflammatory myofibroblastic tumor of other sites
- Beta catenin-, in contrast to fibromatosis
- Low Ki67 proliferative index (Am J Surg Pathol 2010;34:569)
Differential diagnosis
- Fibromatosis (beta catenin+)
- Leiomyoma
- Spindle cell mesothelioma
