Adenoid cystic carcinoma of the breast: case report and review of literature

Abstract

We report the case of a patient who presented with a painful breast lump that turned out to be an adenoid cystic carcinoma of the breast. The literature is reviewed, highlighting the good prognosis associated with this rare condition and the current preferred treatment modalities.

Case History

A 66-year-old woman presented with a lump in her right breast. Examination showed a 2cm mass in the upper outer quadrant of the breast. Mammography showed an asymmetric ill defined mass in that area (with a radiological score of R3) and ultrasonography confirmed a hyperechoic lesion that was 20mm in diameter. A core biopsy confirmed the diagnosis of an adenoid cystic carcinoma (ACC). The patient underwent wide local excision of the right breast lump with sentinel lymph node biopsy and axillary sampling as well as postoperative radiotherapy. Histopathology of the surgically resected specimen confirmed ACC and lymph nodes negative for metastases.

Discussion

ACC of the breast is a rare and slow growing neoplasm that accounts for 0.1% of all breast neoplasms. Of the primary breast tumours, ACC has among the more favourable prognoses: distant metastatic disease and death from the disease are uncommon. This tumour occurs predominantly in postmenopausal women with a mean age of 50–64 years. It is rarely bilateral and has no predilection with respect to laterality. The most frequent presenting symptom is that of a tender breast mass and only a few cases have been detected incidentally in asymptomatic patients.^1,2 While the radiological appearances of ACC are generally non-specific, the diagnosis is confirmed by histological examination of biopsied specimens (Fig 1).²

Figure 1.

Photomicrograph of specimen showing classic cribriform grown pattern of breast adenoid cystic carcinoma (Adapted from Law YM et al 2009)⁷

Oestrogen receptor status in patients with primary breast tumours has been analysed for more than 20 years. Although most authors have found that ACC of the breast lacks oestrogen receptors, conflicting reports from some series suggest that oestrogen receptor status cannot be used to differentiate ACC from other breast cancers.²

One of the studies looking at the prognosis and histological features was carried out by Ro et al who graded ACC of breast into three prognostic groups based on the proportion of solid elements – Grade 1 (no solid element), Grade 2 (<30% solid elements) and Grade 3 (>30% solid elements). They noted that tumours with more solid elements tended to be more aggressive and at higher risk of recurrence and therefore suggested that Grade 1 could be managed by local excision, Grade 2 by simple mastectomy and Grade 3 by mastectomy and axillary clearance.³

Nevertheless, axillary lymph node and distant metastases are rare in ACC of the breast as reported by Arpino et al who noted that nodal metastases only occurred in fewer than ten reported cases in the literature.⁴

Arpino et al analysed 28 patients and showed that ACCs had lower proliferative activity compared to ductal carcinomas and this translated into a more favourable phenotype.⁴

There is no consensus on optimal treatment for patients with ACC of the breast as this is such a rare diagnosis. It is clear that local excision as the sole treatment may lead to unacceptably high rates of local recurrence. A case series by Leeming et al emphasised this by showing that 37% of patients had local recurrence of cancer after receiving local excision.⁵ On the other hand, the low incidence of axillary lymph node metastasis suggests that axillary node dissection is unwarranted. Reported surgical treatment modalities range from a simple lumpectomy with radiotherapy to radical mastectomy.²

In our case, the multidisciplinary team recommended a lumpectomy and lymph node biopsy, and the decision for postoperative radiotherapy was made owing to the high proportion of solid elements on histology, which has been recognised to mark a more aggressive tumour course.⁴

The outcome for treatment in this tumour is excellent with 5-year survival rates of 85 to 90% and 5-year disease free rate of almost 100% for survivors. The Surveillance, Epidemiology and End Results database reported on 712 cases between 1988 and 2001 with relative 5-year survival ranging from 100% in stage I to 96% in stage IV.⁶ The outcome was independent of the type of procedure performed, whether lumpectomy, modified radical mastectomy or total mastectomy with or without axillary node dissection. Despite the excellent prognosis, local recurrence and late distant metastases have been reported to the lungs (commonest site), liver, kidneys and brain.⁴

Conclusions

While ACC of the breast is a rare neoplasm, it is of interest due to its favourable prognosis (~90% survival rate). While there is no consensus on the optimal treatment currently, the role of breast preserving surgery and radiotherapy needs further assessment. However, even though metastatic disease is rare, close follow up is required in these patients to exclude disease recurrence.