Stanford School of Medicine
 use browser back button to return

Surgical Pathology Criteria

Juvenile Fibroadenoma of the Breast


  • Circumscribed, often large, breast mass usually occuring in adolescent females with stromal and epithelial hypercellularity but lacking the leaf-like growth pattern of phyllodes tumors

Alternate/Historical Names

  • Benign cystosarcoma phyllodes
  • Cellular fibroadenoma
  • Cellular adenofibroma
  • Fetal fibroadenoma
  • Juvenile adenofibroma

Diagnostic Criteria

  • Circumscribed
    • Rarely multiple
  • Biphasic stromal and epithelial process
    • Pericanalicular pattern most common
      • May be mixed with intracanalicular
    • Lacks leaf-like growth pattern
  • Uniformly hypercellular stroma
    • Fibrotic areas may be present
    • Lacks atypical features
      • No periductal increase in cellularity
      • No stromal overgrowth
      • No cytologic atypia
      • Mitotic rate < 3/10 hpf
  • Frequent epithelial and myoepithelial hyperplasia
    • May mimic that seen in gynecomastia
    • May be atypical
  • Most patients age 10-20
    • (Most fibroadenomas in adolescents are typical, adult type fibroadenomas and should be diagnosed as such)
  • Giant fibroadenoma
    • Tumors >500 g or disproportionally large compared to rest of breast
    • More frequent in young and black patients
    • We consider the term merely descriptive
    • May be either adult type or juvenile fibroadenomas

Richard L Kempson MD
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342

Original posting:: May 27, 2006

Supplemental studies


  • Stromal cells
    • CD34, Factor XIIIa positive
    • Smooth muscle actin positive more often than in adult fibroadenoma

Differential Diagnosis

(Adult Type) Fibroadenoma Juvenile Fibroadenoma
Hypocellular to variably cellular stroma Uniformly hypercellular stroma


Juvenile Fibroadenoma Low Grade Phyllodes Tumor
No leaf-like architecture Prominent leaf-like architecture
No condensation around ducts Stromal condensation around ducts
Does not infiltrate May infiltrate surrounding breast
The histologic border between these two is not always sharp


Juvenile Fibroadenoma High Grade Phyllodes Tumor
No stromal atypia Atypical stroma
Stromal mitotic rate < 3/10 hpf Elevated stromal mitotic rate
No stromal overgrowth Stromal overgrowth
Does not infiltrate May infiltrate surrounding breast
Stromal overgrowth defined as at least one low power field (40x total magnification) composed entirely of stroma


Juvenile Fibroadenoma Juvenile Papillomatosis
Cellular stroma Paucicellular stroma
Canalicular and tubular epithelium Prominent cysts


Pubertal Macromastia Juvenile Fibroadenoma
Diffuse, not circumscribed Circumscribed
Fibrous or fatty stroma Cellular stroma
Rare More common as a cause of adolescent breast enlargement
Both may cause rapid, massive growth


  • Mean age 15
    • Range 10-39
  • More common in black females
  • Multiple tumors uncommon
  • Frequent rapid growth
  • May recur, especially in patients with multiple tumors
  • No invasion or metastases
  • No increased risk of carcinoma


Biphasic lesions of the breast


  • Rosen PP, Oberman HA. Tumors of the Mammary Gland, Atlas of Tumor Pathology, AFIP Third Series, Fascicle 7, 1993
  • Lerwill MF. Biphasic lesions of the breast. Semin Diagn Pathol. 2004 Feb;21(1):48-56.
  • Dehner LP, Hill DA, Deschryver K. Pathology of the breast in children, adolescents, and young adults. Semin Diagn Pathol. 1999 Aug;16(3):235-47.
  • Powell CM, Cranor ML, Rosen PP. Multinucleated stromal giant cells in mammary fibroepithelial neoplasms. A study of 11 patients. Arch Pathol Lab Med. 1994 Sep;118(9):912-6.
  • Musio F, Mozingo D, Otchy DP. Multiple, giant fibroadenoma. Am Surg. 1991 Jul;57(7):438-41.
  • Raganoonan C, Fairbairn JK, Williams S, Hughes LE. Giant breast tumours of adolescence. Aust N Z J Surg. 1987 Apr;57(4):243-7.
  • Silverman JS, Tamsen A. Mammary fibroadenoma and some phyllodes tumour stroma are composed of CD34+ fibroblasts and factor XIIIa+ dendrophages. Histopathology. 1996 Nov;29(5):411-9.
  • Remadi S, Ismail A, Karpuz V, Finci V, Zacharie S, Vassilakos P. [Cellular (juvenile) fibroadenoma of the breast. A clinico-pathologic and immunohistochemical study of 7 cases] Ann Pathol. 1994;14(6):392-7. French.
  • Fekete P, Petrek J, Majmudar B, Someren A, Sandberg W. Fibroadenomas with stromal cellularity. A clinicopathologic study of 21 patients. Arch Pathol Lab Med. 1987 May;111(5):427-32.
  • Pike AM, Oberman HA. Juvenile (cellular) adenofibromas. A clinicopathologic study. Am J Surg Pathol. 1985 Oct;9(10):730-6.
Printed from Surgical Pathology Criteria:
© 2005  Stanford University School of Medicine