Paraneoplastic pemphigus

 Paraneoplastic pemphigus

Overview

Paraneoplastic pemphigus (PNP) is a rare, severe autoimmune blistering disease triggered by an underlying cancer, often a lymphoma, causing painful blisters and erosions on skin and mucous membranes (especially the mouth). It involves autoantibodies attacking proteins that hold skin cells together, leading to widespread tissue breakdown and potentially fatal complications like bronchiolitis obliterans (lung inflammation). Diagnosis requires clinical signs, biopsies, and specific autoantibody tests, with treatment focused on controlling the underlying tumor and immunosuppression, though prognosis remains poor. 

Symptoms

Mucosal (Mouth/Throat): The most prominent symptom, featuring severe, painful, persistent erosions, ulcers, and crusting, especially on the lips (vermilion border) and tongue. 

Skin: A mix of blisters, erosions, crusts, and red/purple, scaly patches (lichenoid eruptions) that can look like other skin conditions (e.g., lichen planus, bullous pemphigoid). 

Eyes: Conjunctivitis (inflammation) and corneal scarring can occur. 

Lungs: Bronchiolitis obliterans (severe lung damage) is a major complication, causing shortness of breath (dyspnea). 

Complications

Respiratory System: Bronchiolitis Obliterans (BO) is a hallmark, damaging small airways, leading to chronic cough, shortness of breath, and respiratory failure, a leading cause of death.

Skin & Mucosa: Painful, extensive erosions (mouth, eyes, genitals, skin) cause extreme fluid/protein loss, dehydration, malnutrition, and increase infection risk.

Infection & Sepsis: Loss of skin barrier function and immunosuppression make patients prone to severe infections (pneumonia, sepsis).

Eyes: Conjunctival/corneal erosions, inflammation, scarring, eyelid thickening, and potential blindness.

Gastrointestinal System: Severe oral/pharyngeal pain hinders eating; GI bleeding can occur. 

Risk Factors

Hematologic Malignancies (Most Common):

Non-Hodgkin Lymphoma (NHL)

Chronic Lymphocytic Leukemia (CLL)

Castleman Disease (especially in children/adolescents)

Waldenstrom's Macroglobulinemia

Non-Hematologic Neoplasms (Less Common):

Thymoma

Sarcomas

Carcinomas (e.g., breast, colon, lung, skin)

Age: Primarily affects adults 45-70 years old.

Genetics (Potential): Certain HLA alleles (like Drb1*03) may increase susceptibility in some populations. 

Causes

Lymphoproliferative Disorders: The most frequent culprits, including Non-Hodgkin Lymphoma (especially follicular lymphoma), CLL, and Waldenström's macroglobulinemia.

Castleman Disease: A rare disorder of lymph nodes, strongly linked, especially in children.

Thymoma: Tumors of the thymus gland, also common.

Other Cancers: Less commonly, carcinomas (e.g., lung, gastrointestinal), sarcomas, and melanomas. 

Diagnosis

Clinical Presentation:

Major: Painful, persistent mouth sores (stomatitis) and polymorphic skin lesions (blisters, erosions).

Major: An underlying, often hidden, internal cancer (neoplasm), typically a lymphoma.

Histopathology (Skin Biopsy):

Shows intraepidermal acantholysis (cells separating) and necrotic keratinocytes (dying skin cells).

Direct Immunofluorescence (DIF) (on skin biopsy):

Confirms intercellular IgG/C3 deposits in the epidermis (net-like pattern) and often basement membrane zone (BMZ) staining.

Indirect Immunofluorescence (IIF) (Blood Test):

Uses substrates like rat bladder (or monkey esophagus) to detect circulating autoantibodies against various epithelial proteins, crucial for differentiating from other pemphigus types.

Immunoblotting & ELISA (Blood Test - Gold Standard):

Detects specific autoantibodies to desmogleins (Dsg1, Dsg3), desmocollins (Dsc1, Dsc2, Dsc3), and especially plakin family proteins (envoplakin, periplakin, plectin), and A2ML1. 

Treatment

Treat the Underlying Malignancy (Most Crucial):

Surgery: Complete tumor removal is vital, especially for solid tumors, to stop autoantibody production.

Chemotherapy/Radiation: May be needed depending on the cancer type (e.g., lymphomas).

Immunosuppression:

Corticosteroids: High doses (e.g., 1.5 mg/kg/day) are first-line to reduce inflammation.

Rituximab: Effective, especially for lymphomas.

Other Agents: Azathioprine, mycophenolate mofetil, cyclosporine, cyclophosphamide used with variable success.

Supportive Care (Symptom Management):

Wound Care: Gentle cleaning, hydrating dressings (petroleum jelly gauze), and emollients for blisters and sores.

Pain Control: Topical pain relievers.

IVIG (Intravenous Immunoglobulin): Can help before/after surgery to reduce lung damage risk.

Nutritional Support: Essential due to severe oral involvement.

Type of Doctor Department : A dermatologist and an oncologist/hematologist