Mucous membrane pemphigoid

Mucous Membrane Pemphigoid (MMP) is a rare, chronic autoimmune disorder that primarily affects mucous membranes, leading to blistering, inflammation, and potential scarring. Unlike Bullous Pemphigoid, which primarily involves the skin, MMP predominantly affects the soft tissues of the mouth, eyes, nose, throat, and genitals. The disease is caused by autoantibodies targeting proteins within the basement membrane, resulting in subepithelial blister formation.

A subset of MMP called ocular cicatricial pemphigoid (OCP), that causes scarring of the conjunctiva (the inside lining) of the eyes. If left untreated, it can lead to vision loss and permanent eyelid and corneal damage.

Benign Mucosal Pemphigoid (BMP) is an outdated term previously used to describe mild, non-scarring cases of MMP. However, “benign” is misleading because even mild cases can progress and cause significant complications. Today, BMP is generally included under MMP, focusing on non-ocular involvement.

Symptoms vary depending on the mucosal sites affected but can include:

• Oral involvement: Painful blisters, erosions, and ulcers in the mouth, making eating and speaking difficult.
• Ocular involvement (OCP): Chronic eye inflammation that can lead to scarring, vision loss, and blindness if untreated.
• Nasal involvement: Chronic nasal crusting, nosebleeds, and airway obstruction.
• Pharyngeal and laryngeal involvement: Hoarseness, difficulty swallowing, and airway compromise in severe cases.
• Genital involvement: Painful erosions and scarring affecting the vulva, vagina, or penis.

MMP can occur alongside other autoimmune diseases, including:

• Thyroid disease (Graves’ disease, Hashimoto’s thyroiditis)
• Rheumatoid arthritis
• Systemic lupus erythematosus (SLE)
• Inflammatory bowel disease (Crohn’s disease, ulcerative colitis)
• Type 1 diabetes
• Autoimmune blistering diseases (e.g., Bullous Pemphigoid, Pemphigus Vulgaris)

OCP:

Dry eye syndrome and alopecia areata.

MMP is a rare condition, with an estimated incidence of 1 to 5 cases per million people per year. The true prevalence may be higher due to underdiagnosis, especially in cases with mild symptoms or misdiagnosis as other mucosal disorders.

• Age: Most commonly diagnosed in adults over 60, though it can occur at any age.
• Gender: Studies suggest a female predominance, with a 2:1 female-to-male ratio.
• Genetics: Certain HLA gene variants have been linked to a higher risk of developing MMP, suggesting a genetic predisposition
• Geographic Distribution: Cases have been reported worldwide, with no clear ethnic or geographic predisposition.
• Comorbidity:  MMP is strongly associated with other autoimmune diseases, indicating those with thyroid disease (Graves’ disease, Hashimoto’s thyroiditis), rheumatoid arthritis, or lupus may be at a slightly increased risk.

OCP:

Being female, 60 years and older, and using certain medications have been associated with the development of OCP.

• Mucosal immune response in biology, disease prevention and treatment (2025)
• Meeting Report on “10th Anniversary Symposium on Inflammatory Skin Disease” (2024)
• Evaluation of link between COVID-19 adjacent spike in hydroxychloroquine use and increased reports of pemphigus: a disproportionality analysis of the FDA Adverse Event Reporting System (2024)
• Implantation of XEN gel stent in a patient with ocular cicatricial pemphigoid (2023)
• Elevated serum BAFF in patients with ocular cicatricial pemphigoid (2022)
• A novel case of ocular cicatricial pemphigoid induced by levamisole-adulterated cocaine (2021)
• Ocular cicatricial pemphigoid (2020)