Cysts vs. Tumors in Dogs: Key Differences and Veterinary Evaluation

Skin/subcutaneous masses in dogs are common. Distinguishing cysts from tumors guides management.

Cysts

• Fluid-filled, encapsulated sacs
• Usually benign (sebaceous, follicular, dermoid)
• May rupture, become infected
• Often movable, non-painful

Tumors

• Solid tissue proliferation
• Benign (lipoma, histiocytoma) OR malignant (mast cell tumor, soft tissue sarcoma, melanoma)
• Malignant tumors metastasize
• Variable texture, fixation, growth rate

Diagnostic Steps

1. Fine-needle aspiration (FNA) + cytology
2. Biopsy if FNA inconclusive
3. Imaging (X-ray, US, CT) for staging if malignant suspected

Treatment

• Cysts: Monitor, drain, or excise if recurrent/infected.
• Tumors: Surgical excision ± margins; chemo/radiation for malignant.

Any new lump warrants veterinary exam. Early detection saves lives.