What is the cause of chest blisters?

Chest Blisters: Differential Diagnosis and Evaluation

Blisters on the chest require immediate evaluation to distinguish between benign causes (friction, contact dermatitis) and life-threatening conditions (Stevens-Johnson syndrome/toxic epidermal necrolysis, bullous drug reactions, or severe infections). 1

Immediate Life-Threatening Causes to Exclude

Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis (SJS/TEN)

• If blisters are accompanied by fever, malaise, skin pain (like sunburn), or mucous membrane involvement (eyes, mouth, genitals), immediately consider SJS/TEN and hospitalize the patient. 1
• Look for dusky erythema, purpuric macules, or flat atypical target lesions that preceded the blisters 1
• Check for positive Nikolsky sign (epidermis separates with gentle lateral pressure) 1
• SJS involves <10% body surface area (BSA), while overlap SJS-TEN involves 10-30% BSA 1
• Most commonly drug-induced; review all medications started within the past 8 weeks 1

Bullous Drug Reactions from Immune Checkpoint Inhibitors

• If the patient is receiving cancer immunotherapy (anti-PD-1, anti-PD-L1, anti-CTLA-4), bullous dermatoses are a recognized immune-related adverse event. 1
• Grade 2 (blisters 10-30% BSA): Hold immunotherapy, consult dermatology urgently, initiate high-potency topical steroids (clobetasol), consider systemic prednisone 0.5-1 mg/kg/day 1
• Grade 3-4 (>30% BSA or with pain/fluid abnormalities): Permanently discontinue immunotherapy, admit immediately, administer IV methylprednisolone 1-2 mg/kg 1

Chemotherapy Extravasation

• If blisters appear at or near a central venous access device site with acute thoracic pain, suspect extravasation into chest wall tissues. 1
• Confirm with thoracic CT scan 1
• Stop infusion immediately, aspirate through catheter, consider dexrazoxane if anthracycline was extravasated 1
• Blisters may appear days to weeks after initial inflammation 1

Common Benign Causes

Friction Blisters

• Result from repetitive mechanical forces separating epidermis at stratum spinosum level 2
• Typically occur where skin is held tightly to underlying structures 2
• Filled with fluid similar to plasma but with lower protein content 2
• Management: If uncomplicated without pressure pain, leave intact; if pressure-painful, puncture and leave roof in place; if ruptured without infection, leave remnants of roof 3

Contact Dermatitis with Blistering

• Acute allergic or irritant contact dermatitis can produce vesicles or bullae 4
• Distribution corresponds to area of contact with allergen or irritant 4
• Associated with pruritus and erythema 4

Herpes Zoster (Shingles)

• Unilateral dermatomal distribution of grouped vesicles on erythematous base 5, 6
• Pain in dermatomal distribution triggered by touch, often preceding rash by days 5
• Does not cross midline 5

Autoimmune Blistering Disorders

Bullous Pemphigoid

• Most common autoimmune blistering disease, typically in elderly patients 4
• Tense bullae on normal or erythematous skin, often involving flexural areas 4
• Pruritus may precede blisters by weeks to months 4
• Diagnosis requires skin biopsy with direct immunofluorescence showing linear IgG and C3 at basement membrane zone 4
• Treatment: High-potency topical steroids or systemic steroids; consider steroid-sparing agents (IVIG, rituximab) for long-term management 1

Pemphigus

• Flaccid bullae that rupture easily, leaving erosions 4
• Positive Nikolsky sign 4
• Requires direct immunofluorescence showing intercellular IgG deposition 4

Diagnostic Approach

History

• Medication review: Any new drugs in past 8 weeks, especially antibiotics (sulfonamides), anticonvulsants, allopurinol, NSAIDs, or immunotherapy 1
• Systemic symptoms: Fever, malaise, myalgias, weight loss 1
• Pain quality: Burning pain suggests SJS/TEN; dermatomal pain suggests herpes zoster 1, 5
• Mucous membrane involvement: Mouth sores, eye discomfort, genital lesions 1

Physical Examination

• Assess percentage of BSA involved, presence of mucous membrane lesions, and check Nikolsky sign 1
• Examine all skin surfaces and mucous membranes (eyes, mouth, genitals) 1
• Characterize blister morphology: Tense vs. flaccid, grouped vs. scattered, dermatomal vs. random distribution 1, 4
• Look for target lesions, purpuric macules, or dusky erythema 1

Laboratory and Imaging

• For suspected autoimmune blistering: Skin biopsy for routine histology plus perilesional skin for direct immunofluorescence 1, 4
• For suspected SJS/TEN: Dermatology consultation for biopsy; monitor for progression with serial photography 1
• If central line-associated: Thoracic CT scan 1
• Serologic testing (ELISA, indirect immunofluorescence) may be pursued for specific autoimmune diagnoses 1

Critical Pitfalls to Avoid

• Never assume blisters are benign without excluding drug reactions, especially in patients on new medications or immunotherapy 1
• Do not delay dermatology consultation for rapidly progressive blistering or any mucous membrane involvement 1
• Avoid rupturing blisters in suspected SJS/TEN; this increases infection risk and patient discomfort 1
• For friction blisters, draining while maintaining the roof provides pain relief and reduces infection risk 3, 2