What are the small subcutaneous balls in my axilla?

Small Subcutaneous Balls in the Axilla

The most likely diagnosis for small, asymptomatic subcutaneous balls in the axillae that have been present for years is lipomas or epidermoid (sebaceous) cysts, both of which are benign and require no treatment unless they become symptomatic, infected, or cosmetically concerning. 1

Most Common Benign Causes

Lipomas

• Lipomas are the most common benign subcutaneous lesions, typically occurring on the trunk and proximal extremities including the axillae. 1
• These are soft, mobile, painless masses composed of fat tissue that grow slowly over years. 1
• Up to half of fat cells in lipomas may be atypical on pathology, but this does not indicate malignancy. 1
• No treatment is needed unless the lesions are larger than 5 cm, compressing other structures, or suspicious for malignancy. 1

Epidermoid (Sebaceous) Cysts

• These are typically asymptomatic unless they become infected, presenting as firm, round nodules under the skin. 1
• The axillae are a common location due to the high density of hair follicles and sebaceous glands. 2
• Inflamed cysts contain normal skin flora even when uninflamed, and inflammation occurs from rupture of the cyst wall rather than true infection. 2

When to Consider Other Diagnoses

Lymphadenopathy

• Reactive lymphadenopathy from infections is the most common benign cause of axillary masses when lymph nodes are involved. 3
• Bilateral axillary adenopathy suggests systemic processes including infections, inflammatory conditions, or hematologic malignancies. 3
• Lymph nodes are typically firmer, less mobile, and located in specific anatomic chains rather than randomly distributed subcutaneous nodules. 3

Infectious Causes Requiring Treatment

• Furuncles (boils) are infections of hair follicles that extend into subcutaneous tissue, but these are typically painful, tender, inflammatory nodules with overlying pustules—not chronic asymptomatic balls. 2, 4
• Carbuncles involve multiple adjacent follicles and require incision and drainage. 2, 4
• These infectious processes develop over days to weeks, not years, and are accompanied by erythema, warmth, and tenderness. 2

Diagnostic Approach

Clinical Examination

• Lipomas are soft, mobile, and painless; epidermoid cysts are firmer and may have a central punctum. 1
• Multiple small lesions that have been stable for years without pain, redness, or systemic symptoms strongly favor benign diagnoses. 1

When Imaging is Indicated

• Ultrasound can confirm the diagnosis of lipomas or cysts if clinical examination is uncertain. 1
• Deep lesions or those suspicious for malignancy should be evaluated with MRI or CT to exclude involvement of underlying structures or liposarcoma. 1
• For axillary lymphadenopathy concerns, ultrasound can differentiate lymph nodes from other subcutaneous masses. 3

When Biopsy is Needed

• Biopsy is not routinely needed for typical lipomas or cysts that have been stable for years. 1
• Excisional biopsy with complete removal of the cyst wall is the only definitive management for epidermoid cysts, but this is only necessary if they become symptomatic or infected. 1

Management Recommendations

Conservative Management

• Observation is appropriate for asymptomatic, stable lesions that have been present for years. 1
• Small lipomas can sometimes be managed with serial injections of mid-potency steroids if treatment is desired. 1

Surgical Intervention

• Excision is indicated only for lesions larger than 5 cm, those compressing other structures, cosmetically concerning lesions, or those suspicious for malignancy. 1
• Minimal-scar segmental extraction technique is preferred when possible over conventional surgical excision. 1
• For infected epidermoid cysts, incision and drainage with complete removal of the cyst capsule prevents recurrence. 2, 1

Critical Pitfalls to Avoid

• Do not confuse stable, chronic subcutaneous nodules with acute infectious processes like furuncles or carbuncles, which present with pain, erythema, and rapid onset. 2, 4
• Do not routinely culture or biopsy asymptomatic epidermoid cysts, as they contain normal skin flora even when uninflamed. 2
• Do not assume all axillary masses are lymph nodes—subcutaneous lesions like lipomas and cysts are far more common in the general population. 3, 1
• Avoid unnecessary imaging or intervention for clinically obvious benign lesions that have been stable for years without concerning features. 1