Intra-mammary Lymph Nodes(IMLNs) are lymph nodes surrounded completely by breast tissue, a feature that distinguishes them from low lying axillary lymph nodes(AxLNs).
IMLNs have received little attention compared to AxLNs as potential prognostic indicators in breast carcinoma. This ,probably ,is due to the relatively small number of reported cases and the rarity of studies that have focused on IMLNs.
Due to the high variability of the incidence and prevalence of IMLNs, they are sometimes overlooked during clinical and radiological examinations. Some authors believe that IMLNs have no clinical significance unless they get infiltrated by breast cancer. Their clinical implications in this case remain controversial .
Reported pathological affections of IMLNs include malignant conditions as metastatic carcinoma of a clinically evident or occult breast carcinoma and non-Hodgkin's lymphoma.
Other inflammatory conditions such as tuberculosis have also been reported. 
Although IMLNs can be located in any part of the breast, they are most commonly found in the upper outer quadrant. The prevalence of IMLNs has been reported to range between 1% and 28% [2 ].
They are noted in approximately 5% of patients undergoing routine mammography .
At the National Cancer Institute of Cairo University, radiology department records show a description of IMLN in 418 out of 7100 diagnostic sono-mammography examinations performed in 2019, assuming a percentage of 5.9%.
According to the current 8th edition of the American Joint Committee on Cancer AJCC staging system, there is no distinction between axillary and IMLNs, and for the purpose of staging, they are considered axillary LNs. 
Patients with IMLN metastases are considered to be in stage II disease and are described as having positive regional metastasis even if axillary nodes are free. So, the presence of IMLNs metastasis can upstage the disease and change therapeutic decisions.
On the other hand, considerable attention has been paid to the significance of extra-axillary lymph node metastases during sentinel lymph node biopsy (SLNB).Several reports describe the identification of IMLNs as the sentinel node on lymphoscintigraphy in 0.7% and up to 14% of patients undergoing SLNB .
According to MD Anderson Cancer Center experience, disease-free survival (DFS) and overall survival (OS) were significantly affected in breast cancer patients with IMLN metastases whether isolated or associated with axillary node involvement.  Other studies have also shown IMLNs metastasis to be associated with shorter DFS and OS. [6 ] On the other hand, some reports have found that IMLN positive/ AXLN negative patients have better prognosis than IMLN negative /AXLN positive patients. 
On mammography, normal IMLNs can be seen as well circumscribed, homogenous, oval or round densities smaller than 1 cm. They typically have a central lucent hilum, which appears as a lower density at the centre than the periphery. This is called the hilar notch (Doughnut sign).
Suspicious mammographic features of IMLNs are a size larger than 1 cm, change in shape, spiculated margins, loss of the lucent centre or the hilar notch and increased density. IMLNs metastases can also be seen as microcalcifications.
By ultrasonography normal IMLNs appear as well circumscribed, oval or round, homogenously hypoechoic structures with mild posterior acoustic enhancement and an echogenic line representing the hilum .
Suspicious sonographic criteria are: marked hypoechogeneity, thickening of the cortex and alterations in the central echogenic hilum (reduced size, eccentric displacement or absence). Changes in shape can also be present. On the other hand, enlargement to a size more than 1 cm is not considered an absolute diagnostic criteria of metastasis. Peripheral instead of hilar vascularity can also be noted in pathological IMLNs.
A controversy exists regarding optimal management in case of a sentinel IMLN harboring metastasis without identification of sentinel axillary nodes. Some authors believe that a positive sentinel IMLNs does not necessarily predict AxLN metastasis and that the chances of finding further axillary lymph node metastasis is low. Thus, axillary lymph node dissection (ALND) could be spared. The concept behind this opinion is, that axillary staging is dependant on axillary lymph node status and not extra –axillary lymph nodes. 
On the other hand, other authors suggested performing level I ALND for the management of the axilla when only a sentinel IMLN is positive without detection of axillary SLNs. 
Other studies concurred that a sentinel IMLN could act as a real SLN in those cases based on high correlation of metastases between IMLN and AxLNs according to their results. 
Properly characterizing pathological IMLNs and detecting the factors that may influence their prevalence and occurrence in different stages of breast cancer may aid in proper therapeutic decision making and could possibly be of prognostic value.