Fibroadenoma as the most common benign tumor of the female breast in women before age 30 can be accompanied with fibrocystic changes (apocrine metaplasia, cysts and papillary apocrine changes), adenosis, calcifications, and proliferative epithelial changes such as mild, moderate, florid and atypical ductal and lobular hyperplasia. Rarely, lobular and ductal non-invasive and invasive carcinoma may occur within fibroadenoma.

Malignant changes within fibroadenoma are usually an incidental finding following the excision of fibroadenoma.

In 1931 Cheatle and Cutler 1 were the first to describe a carcinoma arising in fiboradenoma.

Azzopardi 2 defined carcinomas involving fibroadenoma as: arising in the adjacent breast tissue engulfing and infiltrating fibroadenoma; in the crevices of a fibroadenoma as well as in the adjacent breast tissue; and carcinoma restricted entirely or at least dominantly to a fibroadenoma.

39 years old female presented to the doctor with a well defined lump in the upper lateral quadrant of the right breast, of two months duration. Any family history of breast malignancies was denied. Axillary lymph nodes were not palpable.

Ultrasonography revealed a partially well circumscribed heterogeneous hypoechoic mass measuring 25 × 16 mm (Figure 1).

In mammography the lesion was partially well circumscribed, solitary and of variable density (Figure 2).

Fine needle aspiration cytology was performed and benign epithelial cells were described in cytology.

Chest X Ray, abdominal ultrasound and all laboratory findings were unremarkable.

Lumpectomy was indicated, but during the procedure the operating surgeon opted for a wide margin of clearance.

The incidence of carcinoma within fibroadenoma is reported to be between 0.1% and 0.3% in a screened population, with a peak age of occurrence between 42 and 44 years 345678. Two-thirds of carcinomas within fibroadenoma are lobular and one-third is ductal or mixed ductal and lobular; lobular carcinoma in situ (LCIS) and DCIS have an approximately equal frequency 67891011121314.

Complex fibroadenomas and proliferative diseases adjacent to fibroadenoma are associated with a slight increase in the risk of breast cancer 614.

In an ongoing study at our Institute, we have found hyperplasia in 3.8% among 250 screened cases of fibroadenoma.

The biological behavior of carcinoma occurring within fibroadenoma does not differ from that of breast carcinoma not related to fibroadenoma 578.

Preoperative clinical criteria and radiological criteria are usually insufficient to suggest that malignant change has occurred in a fibroadenoma, especially in cases with in situ carcinoma.

Because of the heterogeneity of the lesion, FNAC sample is likely to be insufficient for accurate diagnosis, as shown in our case. Hence, the diagnosis of carcinoma arising within fibroadenoma in most instances is made only following excision and histopathological examination of the tumor.

Despite the low percentage of carcinoma occurring within fibroadenoma we consider that each lump should be seriously managed; extirpation and histological examination is recommended.

FNAC is not always a reliable diagnostic tool.

Special caution has to be taken in females older than 35 years presenting with a fibroadenoma.

LCIS: Lobular Carcinoma In Situ; DCIS: Ductal Carcinoma in Situ; FNAC: Fine Needle Aspiration Cytology; USG: Ultrasonography.

Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.

The authors declare that they have no competing interests.

LGL has performed the histological examination and was a major contributor in writing the manuscript. RL and FK were major contributors in designing and writing the manuscript. All authors read and approved the final manuscript.