Dermal lymphatic space invasion→ breast pain with warm, swollen, erythematous skin around exaggerated hair follicles, ☆peau d’orange.
Poor prognosis (50% survival at 5 years). Often mistaken for mastitis or Paget disease. Usually ☆lacks a palpable mass.
"inflammatory" is a misnomer because the classic skin findings are not due to infection but are instead caused by cancerous cells obstructing lymphatic drainage after spreading to the dermal lymphatic spaces.