Nail Tumors

Nail Anatomy & Tumor Intro - Nail It Down!

• Nail Unit Components:
  • Nail Plate: Hard, keratinized structure.
  • Nail Bed: Vascular tissue, beneath plate.
  • Nail Matrix: Germinal tissue, forms plate. Lunula is visible part.
  • Nail Folds: Proximal (PNF), Lateral (LNF). Eponychium (cuticle) protects.
  • Hyponychium: Under distal free edge, forms a seal.
• Nail Tumors:
  • Can be benign or malignant growths.
  • Arise from any nail unit structure.
  • Biopsy is key for accurate diagnosis.

⭐ Longitudinal melanonychia in adults, especially if new, wide (>3 mm), or irregular, warrants biopsy to rule out melanoma.

Benign Nail Tumors - Gentle Giants

• Glomus Tumor:
  • Painful (paroxysmal, cold-sensitive), bluish-red nodule under nail.
  • Hildreth's sign: pain relief with tourniquet.
  • Love's sign: point tenderness.
  • X-ray: well-defined erosion of distal phalanx.
• Myxoid Cyst (Mucous Cyst):
  • Translucent, gelatinous papule/nodule near proximal nail fold (PNF) or DIP joint.
  • May cause longitudinal nail groove.
  • Associated with osteoarthritis.
• Onychopapilloma:
  • Presents as longitudinal erythronychia, melanonychia, or leukonychia.
  • May cause distal V-shaped split or subungual hyperkeratosis.
  • Originates from nail matrix or bed.
• Fibromas (Periungual/Subungual):
  • Flesh-colored, firm papules.
  • Koenen tumors: pathognomonic for Tuberous Sclerosis (multiple periungual fibromas).
  • Can distort nail plate.

⭐ Glomus tumors are notorious for the classic triad: severe pain, localized tenderness, and cold sensitivity.

Malignant Nail Tumors - Bad to the Bone

• Squamous Cell Carcinoma (SCC)
  • Most common nail malignancy.
  • Risks: HPV (16, 18), chronic trauma, radiation, immunosuppression.
  • Appears as: Persistent warty, ulcerative, or destructive lesion; often painful, may bleed.
  • May show bone erosion on X-ray.
  • Dx: Biopsy (full-thickness nail bed).
  • Tx: Mohs surgery, wide local excision, amputation if bone involved.
• Melanoma (Subungual)
  • Acral lentiginous melanoma is the most common histological type.
  • Key sign: New/changing longitudinal melanonychia (band width >3mm, irregular borders/color, proximal widening, nail dystrophy).
  • Hutchinson’s sign: Periungual spread of pigment onto nail fold skin.
  • 📌 ABCDEF rule for suspicion: Age (peak 50-70 yrs), Black/Brown Band ≥3mm or Borders irregular, Change in band or lack of Change with prior ineffective treatment, Digit most common (thumb/hallux > index), Extension of pigment to skin (Hutchinson's sign), Family/personal history of melanoma.
  • Dx: Biopsy (nail matrix).
  • Tx: Wide surgical excision or amputation, sentinel lymph node biopsy (SLNB) based on thickness.

⭐ Hutchinson's sign (pigment spread to the proximal or lateral nail folds) is a key clinical finding highly suspicious for subungual melanoma and warrants urgent biopsy.

Diagnosis & Red Flags - Spot the Suspect

• Assessment: History (onset, changes, symptoms, trauma, relevant cancer history). Clinical exam (morphology, color, size, nail plate integrity, periungual skin).

• Diagnostic Tools:

  • Dermoscopy (Onychoscopy): Crucial for pigmented lesions (distinguish nevi vs melanoma) & vascular patterns.
    • Melanonychia: Irregular lines (color, spacing, thickness), micro-Hutchinson's.
  • Biopsy: Gold standard. Nail matrix biopsy for longitudinal melanonychia; consider type.
  • Imaging: X-ray (bone erosion); MRI/USG (soft tissue extent).

• Red Flags ⚠️ - Suspect Malignancy:

  • ABCDEF Rule (Nail Melanoma):
    • Age (50-70), African/Asian.
    • Band (brown-black), Breadth >3mm / irregular Borders.
    • Change in band (rapid growth/darkening).
    • Digit (thumb, hallux, index; single).
    • Extension (Hutchinson’s sign).
    • Family/personal hx melanoma.
  • Nail destruction, ulceration, bleeding.
  • Rapid growth, unexplained pain.

⭐ Hutchinson's sign (periungual pigmentation) is a critical warning for subungual melanoma.

High‑Yield Points - ⚡ Biggest Takeaways

• Glomus tumor: Most common benign, intensely painful (cold-sensitive), bluish-red spot.
• Squamous Cell Carcinoma (SCC): Most common malignant, often warty/ulcerative, linked to HPV.
• Subungual Melanoma: Presents as longitudinal melanonychia; Hutchinson's sign (periungual pigmentation) is crucial.
• Onychomatricoma: Benign, causes thickened yellow nail with longitudinal splinter hemorrhages/cavities.
• Subungual Exostosis: Benign bony growth, often post-traumatic, confirmed by X-ray.
• Myxoid (Mucous) Cyst: Translucent papule near DIP, can cause nail groove.