Ovary tumor
Sex cord stromal tumors

Author: Kyle C. Strickland, M.D., Ph.D. (see Authors page)
Deputy Editor Review: Debra Zynger, M.D.

Revised: 6 March 2018, last major update February 2018

Copyright: (c) 2002-2018, PathologyOutlines.com, Inc.

PubMed Search: Fibroma[TI] ovary[TIAB]

See also: Cellular fibroma, With minor sex cord elements
Cite this page: Strickland, K.C. Fibroma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/ovarytumorfibroma.html. Accessed April 27th, 2018.
Definition / general
  • Benign fibroelastic tumor of the ovary that can be hypo or hypercellular
Essential features
  • Fibromas are stromal tumors composed of spindled, oval or round cells that produce variable amounts of collagen
  • Benign cellular fibromas can have up to 3 mitoses per 10 HPF
    • Cellular fibromas with ≥ 4 mitoses per 10 HPF are now termed "mitotically active cellular fibromas" and represent tumors of uncertain malignant potential
  • It is important to differentiate benign fibroma from diffuse adult type granulosa cell tumor, a potential mimic
ICD-10 coding
  • Ovarian fibroma (D27.9)
  • Ovarian fibroma, left (D27.1)
  • Ovarian fibroma, right (D27.0)
  • Ovarian fibroma with ascites and pleural effusion (D27.9, R18.8, J90)
  • Accounts for ~4% of ovarian tumors (Cancer 1981;47:2663)
  • Most common sex cord stromal tumor, encompassing ~70% of this category
  • Occur in patients 20 - 80 years, with an average age of ~50
  • Often discovered incidentally
  • Conventional fibromas are bilateral in 5 - 10% of cases, whereas cellular fibromas are invariably unilateral
  • Ovary
  • Meigs syndrome is defined as the presence of an adnexal mass accompanied by ascites and hydrothorax (Am J Obstet Gynecol 1937;33:249, Eur J Obstet Gynecol Reprod Biol 2000;92:199), which occurs in ~1% of patients with ovarian fibroma (Nucci: Gynecologic Pathology, 1st Edition, 2009)
  • Gorlin syndrome (basal cell nevus syndrome) is an autosomal dominant disease characterized by multiple basal cell carcinomas of the skin, as well as odontogenic keratocysts, palmoplantar pits, ectopic calcifications and other abnormalities
    • 2 - 25% of female patients with Gorlin syndrome are found to have ovarian fibromas, which are often bilateral, multinodular and calcified, particularly suspicious in pediatric populations (J Pediatr Adolesc Gynecol 2011;24:e5)
    • Occurs in patients with mutations of the human homologue of the Drosophila gene PTCH (patched)
  • Arise from specialized fibroblasts of the ovarian stroma
Clinical features
  • Most common clinical symptoms are abdominal pain, distension and increased urinary frequency
  • Can be associated with ovarian torsion
  • Up to 30% of patients with large fibromas, cellular fibromas and fibrosarcomas have ascites
  • Diagnosis of ovarian fibroma can be tentatively made grossly (see Gross description) and can often be made at frozen section evaluation
  • Benign lesion characterized by a benign fibroblastic proliferation in the ovary and often adjacent to or continuous with ovarian stroma
Radiology description
  • Important radiologically because appears as a solid mass, mimicking malignancy (Radiographics 2002;22:1305)
  • Ultrasonography typically reveals a large, solid pelvic mass separate from the uterus that appears homogeneous and hypoechoic with posterior acoustic shadowing (AJR Am J Roentgenol 1985;144:1239)
  • CT imaging demonstrates a homogeneous solid tumor with delayed enhancement (Radiographics 2002;22:1305)
  • On MRI, fibromas exhibit a low signal intensity on T1 weighted images and a remarkably low signal intensity (similar to skeletal muscle) on T2 weighted images (J Magn Reson Imaging 1997;7:465)
Prognostic factors
  • In general, fibromas do not recur and are adequately treated by surgical excision
  • Up to 13% of patients with cellular fibromas are found to have adhesions or peritoneal implants at surgery but these patients have benign clinical follow up (Am J Surg Pathol 2006;30:929)
  • Cellular fibromas have been reported to recur (Cancer 1981;47:2663) and these tumors should be viewed as having uncertain malignant potential
Case reports
  • Fibromas are adequately treated by surgical excision
  • Cellular fibromas require follow up due to their uncertain malignant potential
Gross description
  • Nearly all are firm and have a smooth lobulated surface
  • Up to 20% present as pedunculated or polypoid growths on the surface of the ovary (Nucci: Gynecologic Pathology, 1st Edition, 2009)
  • Size range from 1 - 21.5 cm (average 6 cm) (Nucci: Gynecologic Pathology, 1st Edition, 2009)
  • Cut surface of conventional fibroma has a solid white or tan / yellow appearance
  • About 1/4 of all fibromas have cystic changes and about 1/3 of cellular fibromas contain cysts; edema is frequent
  • Calcifications are seen in up to 10% (Nucci: Gynecologic Pathology, 1st Edition, 2009)
  • If associated with ovarian torsion, fibromas will often exhibit hemorrhage and necrosis
  • Cut surface of cellular fibromas may appear fleshy (Cancer 1981;47:2663)
  • In contrast, fibrosarcomas are often large and have a soft cut surface, often containing areas of hemorrhage or necrosis
Gross images

Images hosted on PathOut server:

AFIP images:

Various images

Contributed by Rex Bentley, M.D.

Ovarian fibroma

Images hosted on other servers:



Microscopic (histologic) description
  • Composed of thin spindle cells in a whorled arrangement
  • Nuclei are bland, wavy and fusiform and the cytoplasm is eosinophilic, blending with a variable amount of extracellular collagen
  • Cytologic atypia is rare
  • 10% are hypercellular, containing little intercellular collagen (Fletcher: Diagnostic Histopathology of Tumors, 4th Edition, 2013)
  • Cellular fibromas are composed of small cells arranged in herringbone, cross stitched or storiform patterns
    • Cells contain bland spindled nuclei and can exhibit up to 1 - 3 mitoses per 10 HPF (Cancer 1981;47:2663)
    • In an otherwise typical cellular fibroma, the term "mitotically active cellular fibroma" (MACF) has been proposed for tumors that demonstrate > 4 mitoses per 10 HPF (Am J Surg Pathol 2006;30:929), which should be considered a tumor of uncertain malignant potential
  • Occasionally, sex cord elements are present in fibromas, which do not have any prognostic significance if present in less than 10% of the tumor
    • These tumors can be diagnosed as fibroma with sex cord elements
Microscopic (histologic) images

Images hosted on PathOut server:

Images contributed by Kyle C. Strickland, M.D., Ph.D.:

Fibroma at low power

Fibroma with edematous change

Typical fibroma

Fibroma at high power

Light SF1 staining

CD99 negative

Images contributed by Rex Bentley, M.D.:

Fibroma with dense collagen

Cellular fibroma

Positive stains
Negative stains
Electron microscopy description
  • Ultrastructural examination of typical ovarian fibromas demonstrates numerous thin, elongated cells with intercommunicating cytoplasmic processes admixed with abundant collagen fibrils (Cancer 1971;27:438)
    • Fibrils appear grouped in bundles with a crossbanding pattern composed of a light band bound by two thin dark bands (recurring at intervals of 600 Å)
    • Cells appear to have indistinct cell borders and are compressed by collagenous stroma
    • Little cytoplasm is present, which contains few mitochondria and scant endoplasmic reticulum
    • Nuclei appear elongated and thin, with marked heterochromatin condensation noted at the periphery of the nucleus
  • Ultrastructural examination of malignant ovarian fibroma reveals ovoid to spindle shaped nuclei with a moderate amount of cytoplasm and lipid vacuoles present intra and extracellularly (J Clin Pathol 1998;51:868)
    • Poorly formed adhesions are present between adjacent cells and a discontinuous lamina is present at the cell surface
    • Collagen fibrils can be seen in the interstitium
Molecular / cytogenetics description
Differential diagnosis
Board review question #1
You receive an intraoperative consultation from the surgical team for bilateral multinodular ovarian masses in a 16 year old patient. Biopsy of the lesion demonstrates bland, monomorphic spindled cells with a collagenous stroma. Mutation of which of the following is most likely associated with the patient's condition:

  1. FOXL2
  2. HMGA2
  3. JAZF1
  4. PTCH
  5. Vimentin
Board review answer #1
D. PTCH - these findings are associated with Gorlin syndrome