Based on WHO | Can endometrial cancer cause a skin rash, and how can you distinguish cancer-related rashes from other causes?

Endometrial cancer itself rarely causes a typical “skin rash,” but skin findings can occur for several reasons: treatment-related rashes from chemotherapy or immunotherapy, paraneoplastic (cancer‑related) dermatoses, and, very rarely, cutaneous metastases that appear as nodules or plaques rather than a diffuse rash. Understanding these patterns helps distinguish cancer-associated rashes from common skin conditions like eczema or allergic reactions.

How endometrial cancer can be linked to skin changes

• Treatment-related rashes (common): Standard regimens for recurrent or metastatic endometrial cancer such as carboplatin and paclitaxel combined with an immune checkpoint inhibitor (e.g., dostarlimab or durvalumab) commonly cause rashes. These can be red, bumpy, dry, itchy, and may peel or blister; prior radiation sites can react more severely (radiation recall). ^[1] These rashes are recognized side effects that often improve with moisturizers, sun protection, antihistamines, or topical steroids, and should be reported if they worsen or become painful or infected. ^[1] Similar patterns are noted with carboplatin/paclitaxel plus durvalumab, including dry, itchy, bumpy, or blistering rashes and worse reactions in previously irradiated areas. ^[2] Immune‑related skin toxicity with checkpoint inhibitors can range from mild rash and pruritus to more severe blistering or ulceration, and requires timely evaluation. ^[3]

• Paraneoplastic dermatoses (uncommon): Some skin disorders signal an internal malignancy’s presence or progression. In gynecologic cancers, reported paraneoplastic syndromes include malignant acanthosis nigricans (sudden, extensive velvety darkening of skin folds), tripe palms (thickened, velvety palmar ridges), dermatomyositis (violet eyelid rash with muscle weakness), erythema gyratum repens (rapidly migrating concentric rings), Sweet syndrome (tender red plaques with fever), and acquired hypertrichosis lanuginosa (fine body hair growth). ^[4] Sudden onset of multiple paraneoplastic dermatoses has been described in someone with a history of endometrial cancer and may precede discovery of recurrence or metastasis. ^[5]

• Cutaneous metastases (very rare): Endometrial carcinoma metastasizing to skin is rare, historically estimated around 0.8–1% of cases, and typically presents as firm subcutaneous nodules or plaques rather than a flat, diffuse “rash.” ^[6] When present, these lesions often reflect widespread disease and carry a poor prognosis, so biopsy confirmation is important. ^[7]

Distinguishing cancer-related rashes from other causes

• Onset and context: A rash that starts soon after chemotherapy or immunotherapy and matches known side effects (red, itchy, bumpy, peeling) is more likely treatment‑related. ^[1] If a rash appears or worsens on areas previously irradiated, think of radiation recall. ^[8] If the rash begins without new drugs and has atypical features (sudden widespread velvety darkening, concentric rings, tender plaques with fever), consider paraneoplastic dermatoses. ^[4]

• Morphology (appearance):

  • Drug/immune‑related: diffuse maculopapular (red, bumpy) eruption, xerosis (dryness), pruritus, possible blistering; may involve trunk/extremities and spare mucosa unless severe. ^{[1] [2]}
  • Radiation recall: sharply demarcated redness, blistering, or ulceration confined to previously irradiated fields. ^{[8] [3]}
  • Paraneoplastic: characteristic patterns (e.g., velvety hyperpigmentation of folds in acanthosis nigricans, violaceous eyelid rash in dermatomyositis, target‑like or concentric ring lesions in erythema gyratum repens). ^[4]
  • Cutaneous metastases: discrete, firm, often painless nodules or plaques in the skin or subcutis; can ulcerate; typically not itchy “rashes.” ^{[6] [7]}

• Associated symptoms:

  • Immune‑related events may accompany other systemic issues (thyroid changes, joint pain, diarrhea). ^[9]
  • Paraneoplastic syndromes can coincide with constitutional symptoms or signal tumor progression. ^{[4] [5]}
  • Metastatic nodules may be accompanied by signs of advanced disease elsewhere. ^[7]

• Temporal pattern:

  • Drug rashes often emerge days to weeks after starting therapy and may improve with supportive care or dose adjustment. ^[1]
  • Paraneoplastic skin changes can precede or coincide with recurrence; sudden onset warrants a cancer work‑up. ^{[4] [5]}
  • Metastatic lesions may appear months to years after the primary diagnosis and progress despite topical treatments. ^[7]

What to do if you notice a rash during treatment

• Report promptly: Even mild rashes with checkpoint inhibitors should be reported early because they can progress; timely care helps prevent severe skin toxicity. ^[9] Immune‑related rashes can include full‑thickness involvement and ulceration in rare cases. ^[3]
• Supportive care: Gentle, non‑perfumed moisturizers, sun protection (SPF 50+), avoiding scratching/tight clothing, antihistamines, and topical steroids are commonly recommended for treatment‑related rashes. ^{[1] [2]} Follow your clinician’s instructions and seek care if pain, pus, or spreading occurs. ^[10]
• Targeted evaluation: If the skin change is unusual (nodules, plaques, ring‑like patterns, sudden severe hyperpigmentation), ask about biopsy and systemic evaluation; biopsy confirms metastasis and guides management. ^[7] Dermatology consultation can help identify paraneoplastic patterns linked to gynecologic malignancies. ^[4]

Red flags suggesting a cancer-associated process

• Firm nodules or plaques rather than a flat, itchy eruption. ^{[6] [7]}
• Rash confined to a prior radiation field, with blistering or ulceration. ^{[8] [3]}
• Characteristic paraneoplastic patterns, such as tripe palms or sudden widespread acanthosis nigricans. ^[4]
• Systemic symptoms (fever with tender plaques, new muscle weakness, rapid progression), or new skin findings during known cancer recurrence. ^{[4] [5]}

Practical comparison table

Scenario	Typical look	Timing	Key clues	Next steps
Chemotherapy/immunotherapy rash	Red, bumpy, itchy; may peel or blister	Days–weeks after starting treatment	Common with carboplatin/paclitaxel ± checkpoint inhibitor	Report early; moisturizers, antihistamines, topical steroids, sun protection; adjust therapy if needed [1] [2] [3]
Radiation recall	Redness, blistering, ulceration limited to prior radiation area	During or after chemo	Strictly within irradiated field	Stop triggering agent if severe; local care; clinician assessment [8] [3]
Paraneoplastic dermatoses	Patterned changes (acanthosis nigricans, tripe palms, dermatomyositis, Sweet syndrome)	Can precede or signal progression	Distinctive morphology, rapid onset	Dermatology consult; cancer work‑up for recurrence/progression [4] [5]
Cutaneous metastases	Firm nodules/plaques, possibly ulcerated	Months–years after cancer	Discrete masses, poor response to topical therapies	Biopsy to confirm; systemic staging; palliative/local treatments [6] [7]

Bottom line

• Endometrial cancer itself does not typically cause a diffuse “rash,” but skin changes are relatively common due to modern treatments, and rarer cancer‑related skin syndromes or metastases can occur. ^{[1] [2] [4]}
• The appearance, location, timing, and associated symptoms help differentiate treatment side effects from paraneoplastic dermatoses or true skin metastases. ^{[1] [8] [4] [7]}
• Prompt reporting and appropriate evaluation (including biopsy for nodules) are important to ensure safe treatment and detect potential recurrence. ^{[9] [7]}