juvenile mammary fibroadenoma
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.
Synopsis
Most patients age 10-20
Most fibroadenomas in adolescents are typical.
Circumscribed
Rarely multiple
Biphasic stromal and epithelial process
Cellular stroma
Canalicular and tubular epithelium
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/hpf
Frequent epithelial and myoepithelial hyperplasia
May mimic that seen in gynecomastia
May be atypical
No leaf-like architecture
No condensation around ducts
Does not infiltrate
No stromal atypia
Stromal mitotic rate < 3/hpf
No stromal overgrowth
Differential diagnosis
adult-type fibroadenomas
- hypocellular to variably cellular stroma
low-grade phyllodes tumor
- Prominent leaf-like architecture
- Stromal condensation around ducts
- May infiltrate surrounding breast
- The histologic border between these two is not always sharp
high-grade phyllodes tumor
- Atypical stroma
- Elevated stroma mitotic rate
- Stromal overgrowth
- May infiltrate surrounding breast
- Stromal overgrowth defined as at least one low power field (40x total magnification) composed entirely of stroma
juvenile papillomatosis
- Paucicellular stroma
- Prominent cysts
Differential diagnosis: mammary biphasic lesions
adenomyoepithelioma
mammary fibroadenomas
- mammary juvenile fibroadenoma
mammary hamartoma
metaplastic mammary carcinoma
phyllodes tumor
pleomorphic adenoma
gynecomastia
pubertal macromastia
Credits
References
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.