MMP Flashcards
(20 cards)
What is the demographic most affected by MMP?
Elderly individuals aged 60–80 years, with a higher prevalence in females than males.
MMP stands for Mucous Membrane Pemphigoid, a rare chronic disease.
What type of antibodies are involved in the pathogenesis of MMP?
Autoreactive IgG antibodies directed against various antigens in the anchoring filament zone.
This is different from hemidesmosomal plaque involvement seen in conventional Bullous Pemphigoid (BP).
Name the three well-defined subgroups of MMP.
- Anti-epiligrin MMP
- Ocular MMP
- Anti-BP antigen MMP
Each subgroup targets different antigens and has unique clinical features.
What is the target antigen for Anti-epiligrin MMP?
Laminin 332 (laminin 5, epiligrin).
This subgroup is strongly associated with underlying solid organ malignancy, particularly adenocarcinoma of the upper aerodigestive tract.
What is the most common site of involvement in Oral MMP?
Gingiva, buccal mucosa, and palate.
Oral involvement is characterized by erythema, erosions, and painful chronic lesions.
What is the target antigen for Ocular MMP ?
The β4 subunit of α6β4 integrin.
It is nearly exclusively associated with ocular involvement.
What are the common mucosal clinical features of MMP?
■ Oral (#1 site): 90%, gingiva, buccal mucosa, and palate (> tongue, lips); p/w erythema and erosions of gingiva (desquamative gingivitis), painful chronic erosions (especially palate), and rarely blisters. periodontal ligament damage and loss of teeth
■ Conjunctiva (#2 site): 40% bilateral > unilateral; begins as non-specific conjunctivitis → subepithelial conjunctival fibrosis → symblepharon (adhesion of bulbar and palpebral conjunctivae), trichiasis (inward facing eyelashes), entropion, ectropion, and xerosis → trauma induces corneal neovascularization, ulceration, and BLINDNESS
■ Other mucosal: 1/3 nasopharyngeal/upper aerodigestive tract (epistaxis and airway obstruction); laryngeal (hoarseness, life-threatening stenosis); esophageal (dysphagia and strictures); anogenital (strictures and obliteration of orifices)
Mucosal sites are more susceptible than skin.
What is the histopathological finding in MMP compared to BP?
Fewer eosinophils, predominantly lymphocytes and plasma cells, and increased dermal fibrosis/scarring.
This reflects the chronic nature of the disease.
What is the first-line treatment for mild-moderate ocular, oropharyngeal and cutaneous disease in MMP?
Dapsone, often combined with potent topical or intralesional steroids.
Other options include tetracyclines and short courses of oral steroids.
What is the treatment of choice for severe or progressive ocular or oesophageal/laryngotracheal disease in MMP?
Cyclophosphamide 1-2mg/kg/day along with systemic steroids or steroid-sparing immunosuppressives.
Surgical correction of severe ocular scarring can only be attempted after the disease is controlled.
Describe the skin features of mmp
Skin involvement (25%): fewer lesions, different distribution and morphology than conventional BP
○ Most common sites: scalp/face/neck and upper trunk
○ Erythematous plaques and recurrent blisters/erosions → heal w/ atrophic scars (not seen in BP)
What is the most reliable lab test, sens, for MMP, findings
DIF. Sens 80-90%. more +ve in mucosal sites than skin.
linear IgG (IgG1, 4), less freq - IgA, and/or C3 along BMZ; may require multiple biopsies for DIF to increase test sensitivity
Is IIF helpful to sx MMP, finding?
- Can be detected in serum samples of 20-30%
- Usually IgG, but IgA, IgE and less frequently IgM can be detected
- Sensitivity can be increased by using normal oral or genital mucosa and conjunctiva, or salt-split skin
○ If using salt split skin, most binding epidermal side, but with laminin 332 MMP, binding is to the dermal side
○ IIF microscopy - knockout skin substrates - to distinguish btw EBA, anti-laminin 332
What are the resutls in salt-split skin test for MMP
- Salt-split skin: mixed epidermal/dermal or epidermal deposition with IgG for most patients with MMP (anti-epiligrin [anti-laminin 332] MMP = dermal/floor staining)
DDx of MMP
- BP/EBA/LADA
- PV, erosive LP, bachets
- End-stage scarring stages may minic:
○ Infectious conjunctivitis
○ Ocular pseudopemphigoid (due to ophthalmic solutions such as pilocarpine, b-blockers)
Late stage SJS and TEN
What is the prognosis of MMP
- Chronic, potentially devastating, rarely fatal disease
- Vision impairment = main complication
- Can lead to weight loss as well as resp, sexual and urinary complications
Life threatening complications – due to severe laryngeal, tracheal or oesophageal disease rare
describe local tx for MMP, and other systemic agnets
LCOAL
○ Mouth responds well to potent TCS (mouthwash/topical formulation), tetracycline mouth washes and good hygiene
○ Nasal/pharynx/larynx spray/inhaled CS
○ Recalcitrant lesions may need ILCS
○ AZA and MMF known to be good at partially controlling ocular and skin
○ sCS alone usually not effective for severe disease poorer at controlling mucosal than skin disease
* Others of help:
○ Tetracycline in comb with nicotinamide
○ Topical tacrolimus
○ CsA (topical or systemic)
○ Thalidomide
○ Recent studies suggest MTX, IVIg, TNF-inhibitors such as etanercept and in particular rituximab may be helpful for ocular disease
Surgical intervention may be needed (after disease controlled)
What are the culprits of drug induced LABD
V A N C
Vancomycin - no1
Abx (penicilins), ACE-i captopril
NSAIDs
Cephalosporins
What AI conditions and malignancies are a/w LABD
DM, thyroid, SLE, RA, AI haemolytic anaemia.
B-cell lymphoma, CLL, ca bladder/thyroid/colon/oesophagus
How does the appearance of drug indiced LABD differ
May have TEN-linke or morbiliform appearance, need DIF and bx
