Pea-Sized Hand Lump: Differential Diagnosis & When to See a Doctor

A pea-sized (~5–10 mm) hand lump has a **narrow differential** — most are benign.

Common Causes

Diagnosis	Features	Typical Location
Ganglion cyst	Fluid-filled, fluctuant, transilluminates, may vary in size	Dorsal wrist (60–70%), volar wrist, finger base
Lipoma	Soft, mobile, doughy, non-tender, slow-growing	Anywhere subcutaneous
Epidermal inclusion cyst	Firm, central punctum, keratin expressible, may inflame	Palmar, finger pulp
Giant cell tumor of tendon sheath	Firm, fixed to tendon, slow-growing	Volar finger/hand
Foreign body / splinter	History of trauma, possible granuloma	Palmar
Insect bite reaction	Itchy, erythematous, transient	Anywhere
Neuroma (Morton's, digital)	Tinel's sign, shooting pain, localized	Web space, digital nerve

Rare but Serious

• Skin cancer (SCC, BCC, melanoma) — changing, ulcerated, pigmented
• Soft tissue sarcoma — deep, fixed, >5 cm, growing (rare in hand)
• Metastasis — extremely rare primary site

When to Seek Evaluation

• Painful, growing, or changing
• Numbness/tingling (nerve compression)
• History of trauma
• Skin changes over lump
• Patient anxiety — reassurance has value

Diagnostic Path

1. History + physical (transillumination, Tinel's, mobility)
2. Ultrasound (first-line imaging — cystic vs. solid, vascularity)
3. MRI if deep/complex/surgical planning
4. Biopsy only if imaging suspicious

Most hand lumps are benign ganglia or lipomas. But "pea-sized" doesn't guarantee benign — get it examined.