Why Does My Armpit Hurt?

Check out this answer from Consensus:

Armpit pain can arise from various conditions, each requiring specific diagnostic and therapeutic approaches. If you experience persistent or severe armpit pain, it is crucial to seek medical evaluation to determine the underlying cause and appropriate treatment.

Experiencing pain in the armpit can be concerning and uncomfortable. There are several potential causes for this type of pain, ranging from nerve compression to skin conditions. This article explores some of the common reasons for armpit pain, supported by recent research findings.

Thoracic Outlet Syndrome (TOS)

Thoracic Outlet Syndrome is a condition where the nerves, arteries, and veins running through the armpit become compressed. This compression can lead to symptoms such as pain, numbness, and impaired circulation in the neck, shoulder, arm, or hands. TOS is often caused by the compression of structures in the shoulder area. Treatment typically involves restoring the proper alignment of the shoulders to relieve pressure on the nerves, veins, and arteries1.

Hidradenitis Suppurativa (HS)

Hidradenitis Suppurativa is a chronic skin disease that causes painful boils in areas such as the armpits and groins. This condition affects about 1% of the population and is more common in women. HS can lead to significant inflammation, pain, itching, scarring, and disfigurement. The pain associated with HS can be severe and is often accompanied by depression and anxiety, which can further influence the experience of pain2 3 4.

Neoplasm Involving the Upper Thoracic Root

In some cases, severe or progressive pain in the armpit may be indicative of a malignant pathology. Neoplasms affecting the upper thoracic nerve roots can present with axillary pain. Electrodiagnostic testing and imaging are essential for diagnosing such conditions, as they can reveal abnormalities and the presence of neoplasms5.

Intercostobrachial Nerve Lesion

Post-surgical complications, particularly after axillary lymphonodectomy during mastectomy, can lead to severe pain and paraesthesia in the armpit region. This discomfort is often caused by a lesion in the intercostobrachial nerve. Differential diagnosis should consider potential injury to the brachial plexus or local metastasis6.

Axillary Web Syndrome (AWS)

Axillary Web Syndrome frequently develops following axillary lymph node dissection but can also be caused by infections or strenuous exercise. AWS is characterized by pain, tension, and a taut rope-like structure in the armpit area, often limiting shoulder movement. Idiopathic cases of AWS have also been reported, where the cause is unknown. Treatment typically involves nonsteroidal anti-inflammatory drugs and physical therapy, leading to complete recovery without sequelae7.