Ductal carcinoma in situ of the breast arising in encapsulated mammary hamartoma ; A case report

Concurrent invasive ductal carcinoma and ductal carcinoma in situ arising inside and outside a breast hamartoma: A case report

BACKGROUND

Breast hamartomas are rare benign breast tumors, with an incidence rate of 0.8%-4.8%. Further, the coexistence of hamartomas and carcinoma is also uncommon. Our case report presents a unique instance where invasive ductal carcinoma (IDC) and ductal carcinoma in situ were found both inside and outside a breast hamartoma. This is the second case reported in the literature.

CASE SUMMARY

A 51-year-old woman presented with a 6.0 cm breast tumor on mammography and ultrasound, with suspicious areas indicative of malignant transformation. Biopsy of the suspicious area confirmed IDC with intraductal carcinoma. Breast magnetic resonance imaging showed typical hamartoma changes with irregular areas of abnormal enhancement both inside and outside. A breast-conserving surgery was performed, and postoperative pathology confirmed mammary hamartoma, concurrent with IDC and intraductal carcinoma occurring both inside and outside the hamartoma. Subsequently, appropriate adjuvant therapy was initiated. Currently, the patient is in good condition. Breast cancer may be located both inside and outside the ipsilateral mammary hamartoma, which is difficult to detect preoperatively, especially when there is a focus of intraductal carcinoma, requiring accurate assessment of the tumor extent by modern imaging techniques. Early detection of the coexistence of cancer is clinically important as it can alter patient management.

CONCLUSION

This case emphasizes the importance of modern imaging techniques in accurately evaluating mammary hamartomas associated with malignancies prior to surgery.

Breast hamartomas associated with epithelial atypia and malignancy: are there specific clinical, radiological or pathological features that identify at risk patients?

PURPOSE

Breast hamartomas are rarely associated with epithelial atypia or malignancy. Since the introduction of digital mammography in the UK from 2008, hamartoma detection has increased. The aim of this study was to identify if there are characteristic clinical, radiological or histological features that distinguish hamartomas with intralesional atypia/malignancy (complex hamartomas, CH) or ipsilateral/contralateral atypia/malignancy (non-CH) from those without atypia/malignancy at diagnosis (other benign hamartomas, BH).

METHODS

We performed a retrospective single-institution review of 450 hamartomas reported between 2010 and 2023. Anonymised H&E sections and imaging of CH and non-CH were reviewed to identify distinguishing features.

RESULTS

13,441 benign breast lesions were biopsied/resected between 2010 and 2023 including 450 hamartomas (3.3%), 19 of which (4.2%) were associated with atypia or malignancy. 14 were analysed further (7 CH; 7 non-CH). The mean age of CH plus non-CH patients was significantly higher than patients with BH (47.5 vs. 40.6 years; p = 0.03). The mean size of CH was greater than non-CH (32.1 mm vs.17.6 mm; p = 0.06). There was a statistically significantly higher incidence of atypical/malignant lobular lesions (ALH/LCIS/ILC) in CH vs. non-CH (42.9% vs 0%; p = 0.05). MRI was performed in 2 CH and 3 non-CH; in all 5 the associated malignancy was detected. There was no significant difference between the CH and non-CH group in ultrasound/mammographic features, other hamartoma histological features or other associated benign breast changes.

CONCLUSIONS

Ultrasound/mammogram are not sufficiently sensitive to identify hamartomas with associated atypia/malignancy. Certain hamartoma features may preferentially be associated with atypia/malignancy and which merit further radiological and/or detailed histological investigation.