Dramatic increase in volume versus length of invasive ductal carcinoma mimicking intramammary lymph node in a small nodular lesion.

Background: The tumor growth pattern in breast cancer appears to be variable and unpredictable. A minor increase in size in a pre-existing lesion, especially under 1 cm, corresponds to a more pronounced increase in volume.

Case Presentation: We report a 63-year-old woman with a nodular density mimicking intramammary lymph node, diagnosed as invasive carcinoma of luminal B subtype. The lesion increased size and density over time in following mammograms until having indistinct margins. While the tumor volume was 12.7 mm at the first observation on mammography, it has increased approximately 6.7 times to reach 85.7 mm in four years. Finally, the patient diagnosed with early-stage breast cancer (T1N0M0) was treated with breast-conserving surgery.

Conclusions: Minor changes in size, density, and margin status of a lesion on serial mammograms are warning for breast cancer. Withal, a slight increase in lesion size in two dimensions can result in significant differences in volume. Therefore, comparative evaluation with previous mammograms and observing any difference in morphological features by screening are crucial for early diagnosis and optimal management of the disease.