Juvenile Fibroadenoma of the Breast

Definition

• 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

Immunohistology

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

Differential Diagnosis

• (Adult type) fibroadenoma
• Low grade phyllodes tumor
• High grade phyllodes tumor
• Juvenile papillomatosis
• Pubertal macromastia

Clinical

• 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

Lists

Biphasic lesions of the breast

• Adenomyoepithelioma
• Fibroadenoma
• Gynecomastia
• Hamartoma
• Juvenile Fibroadenoma
• Metaplastic Carcinoma
• Phyllodes Tumor
• Pleomorphic Adenoma
• Pubertal Macromastia

Bibliography

• 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.