BMZ, adhesion molecules, AISBDs Flashcards

1
Q

What is the keratin composition of intermediate filaments?

A

Keratin-5 (basic), keratin-14 (acidic)

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2
Q

Define intermediate filament

A

Connection between the keratinocyte nucleus to hemidesmosomes on the keratinocyte membrane. Responsible for structure of basal keratinocytes

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3
Q

What is the composition of the inner plaque of the hemidesmosome?

A

Plectin
BPAG1-e

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4
Q

What is the composition of the outer plaque of the hemidesmosome?

A

Integrin alpha6beta4
collagen XVII (cytoplasmic domain)

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5
Q

Define anchoring fibrils

A

Connections extending from lamina densa to collagen fibers in the dermis

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6
Q

What is the collagen composition of anchoring fibrils?

A

Collagen VII

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7
Q

Define integrins

A

Cell adhesion molecules that connect the extracellular matrix to the cytoskeleton

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8
Q

What family is BPAG1-e a member of?

A

Plakins

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9
Q

What autoimmune conditions in dogs may result from autoantibodies against BPAG1e?

A

Bullous pemphigoid, MMP

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10
Q

Which classes of adhesion molecules (CAMs) operate independent of Ca++?

A

integrins, IgCAMs

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11
Q

Which classes of adhesion molecules (CAMs) are dependent on Ca++?

A

cadherins, selectins

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12
Q

What class of adhesion molecules is present on leukocytes, allowing for leukocyte adhesion to the endothelium?

A

Integrins

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13
Q

What type of integrins bind leukocytes to the endothelium?

A

Beta2

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14
Q

What type of integrins bind T-cells to APCs?

A

Beta2

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15
Q

What beta2 chain is common to many integrins?

A

CD18

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16
Q

What is a primary role of beta3 integrins?

A

Clotting

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17
Q

What integrin on T-cells binds to ICAM-1 on APCs to allow for successful antigen recognition?

A

LFA-1

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18
Q

What integrin on endothelial cells is important for extravasation of leukocytes when bound?

A

ICAM-2 (bound by LFA-1 on neuts)

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19
Q

What does alpha6beta4 bind to extracellularly?

A

Laminin 332

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20
Q

In what layer(s) of the epidermis are integrins expressed?

A

Stratum basale only

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21
Q

What cell adhesion molecule is present on inflamed endothelial cells and binds VLA-4 to allow for generation of ROS?

A

VCAM-1 (CD106)

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22
Q

What are the classical type 1 cadherins?

A

E-cadherin, N-cadherin, P-cadherin

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23
Q

What cell types express N-cadherin?

A

Myocytes, neurons, fibroblasts

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24
Q

What are the classical type 2 cadherins?

A

VE-cadherin, M-cadherin

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25
Q

What cadherin becomes temporarily dysregulated to allow for diapedesis?

A

VE-cadherin

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26
Q

What is the major autoantigen in human PF?

A

Desmoglein-1

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27
Q

What is the major autoantigen in canine PF?

A

Desmocollin-1

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28
Q

What is the autoantigen in pemphigus vulgaris?

A

Desmoglein-3

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29
Q

Describe the locations of desmogleins 1-3 in the epidermis

A

Desmoglein-1: superficial epidermis
Desmoglein-2: basal layer
Desmoglein-3: deep epidermis

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30
Q

Name two major functions of selectins

A
  1. Mediate initial low-affinity adhesion of WBC to endothelium
  2. Lymphocyte homing
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31
Q

What cell types express P-selectin?

A

Endothelial cells, platelets

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32
Q

What structures within endothelial cells store P-selectin?

A

Weibel-palade bodies

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33
Q

What structures within platelets store P-selectin?

A

alpha granules

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34
Q

What activates P-selectin?

A

Histamine, thrombin

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35
Q

What cells express E-selectin?

A

Endothelial cells

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36
Q

What triggers activate E-selectin?

A

IL-1, TNF, LPS

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37
Q

What cells express L-selectin?

A

Leukocytes (NOT endothelial cells)

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38
Q

What dog breed is reported to be associated with canine leukocyte adhesion deficiency (CLAD)?

A

Irish Setters

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39
Q

Describe the pathogenesis of canine leukocyte adhesion deficiency

A

Single missense mutation in beta2-integrin subunit gene –> cysteine replaced by serine at AA36 –> disulfide bond disruption in CD18 leading to less WBC binding –> recurrent infections despite normal or high WBC counts

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40
Q

How would you diagnose CLAD?

A

PCR (can be done on oral swab)

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41
Q

What cow breed has been reported in bovine leukocyte adhesion deficiency (BLAD)?

A

Holstein

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42
Q

Describe the pathogenesis of BLAD

A

Point mutation in CD18 gene –> aspartic acid replaced by glycine –> dysfunctional integrin assembly and lack of WBC diapedesis

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43
Q

What are the 4 major types of adhesive structures in the epidermis?

A

Adherens junctions, desmosomes, tight junctions, hemidesmosomes

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44
Q

What histologic stain could be useful to highlight the BMZ?

A

PAS

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45
Q

Name the layers of the basement membrane zone

A

Basal keratinocyte –> basal lamina (lamina lucida + lamina densa) –> sublamina densa

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46
Q

Know the locations of various molecules in each layer of the BMZ

A
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47
Q

Define the location of hemidesmosomes

A

Found along the ventral aspect of the basal keratinocyte

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48
Q

Name the 4 components of a hemidesmosome

A

BPAG-1
plectin
integrin alpha6beta4
collagen XVII

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49
Q

What is the molecular target of epidermolysis bullosa simplex in cattle and dogs?

A

KRT5

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50
Q

What is the molecular target of epidermolysis bullosa simplex in cats?

A

KRT14

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51
Q

What is the molecular target of epidermolysis bullosa simplex in Eurasier dogs?

A

Plectin

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52
Q

What is the molecular target of junctional epidermolysis bullosa in cattle?

A

ITGA6 (integrin alpha6), ITGB4 (integrin beta4)

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53
Q

What is the molecular target of junctional epidermolysis bullosa in sheep?

A

ITGB4 (integrin beta4)

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54
Q

What would be considered the primary inflammatory cell infiltrate in bullous pemphigoid in dogs?

A

Eosinophils

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55
Q

What is the target of bullous pemphigoid in dogs?

A

NC16A domain of collagen XVII

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56
Q

What does PAS stain in the lamina densa?

A

Nidogen and perlecan (proteoglycans)

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57
Q

What component of the basement membrane zone forms a hexagonal meshwork/lattice?

A

Collagen IV (lamina densa)

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58
Q

What is the main molecular target of epidermolysis bullosa acquisita (EBA) in dogs?

A

Collagen VII (esp NC1 domain)

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59
Q

What is unique in regards to EBA compared to other acquired AISBDs in dogs?

A

Age of onset- EBA has young onset (1-2 years though puppies may be affected), other AISBDs have 5-6 year of age onset

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60
Q

The “floor” stains on indirect immunofluorescence on salt split mucosa. What is/are the most likely differential(s)?

A

EBA
JEBA
bullous SLE
MMP (can be roof or floor)
mixed AISBD

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61
Q

The “roof”/epidermal side stains on indirect immunofluorescence on salt split mucosa. What is/are the most likely differential(s)?

A

BP (others: MMP, linear IgA)

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62
Q

There is “mixed” staining on indirect immunofluorescence on salt split mucosa. What is/are the most likely differential(s)?

A

MMP (usually roof stains but can be both)
JEBA

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63
Q

A ragged, intracellular split occurs on PAS staining of a suspect AISBD. What is the most likely differential?

A

EB simplex (targets KIF)

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64
Q

What is the major autoantigen in MMP?

A

NC16A domain of collagen XVII (BPAG2)
–BPAG1e and laminin 332 also reported

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65
Q

What is the major autoantigen in canine JEBA?

A

Laminin 332

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66
Q

What antigens stain on the floor of salt-split skin?

A

Laminin 332, collagen IV, collagen VII

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67
Q

What antigens stain on the roof of salt-split skin?

A

K5, K14, plectin, BPAG1, BPAG2, integrin alpha6beta4

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68
Q

What is the most common AISBD in dogs?

A

MMP

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69
Q

What dog breed has a suspected genetic predisposition to EBA?

A

Great Dane (and less so GSP)

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70
Q

What 3 collagen types are part of the BMZ?

A

Collagen XVII (hemidesmosome)
Collagen IV (lamina densa)
Collagen VII (sublamina densa)

71
Q

What do KIF attach to within the BMZ?

A

BPAG1 and plectin on inner plaque

72
Q

What does integrin alpha6beta4 bind to in the BMZ?

A

Inner plaque: BPAG1, plectin
Outer plaque: BPAG2
Lamina densa: laminin-332

73
Q

What collagen type makes up most of the lamina densa?

A

Collagen IV

74
Q

What collagen type makes up the anchoring fibrils that link the lamina densa to the sublamina densa?

A

Collagen VII

75
Q

What parts of the BMZ are secreted by dermal fibroblasts?

A

Collagen IV, Collagen VII, laminin 332, laminin 311, laminin 511

76
Q

Is epidermolysis bullosa cell-rich or cell-poor?

A

cell-poor

77
Q

What cells secrete MOST components of the BMZ?

A

basal keratinocytes

78
Q

What is another name for collagen XVII?

A

BPAG2

79
Q

What is considered a crucial step in hemidesmosome assembly?

A

Binding of integrin alpha6beta4 to laminin-332

80
Q

What structure of the BMZ looks like a cross?

A

Laminin-332

81
Q

Are footpads commonly affected in canine bullous pemphigoid?

A

No (this helps differentiate it from EBA)

82
Q

What breed is overrepresented in MMP?

A

GSD

83
Q

Are footpads typically involved in MMP?

A

No

84
Q

Is MMP rapidly or slowly progressive?

A

Slowly

85
Q

Is EBA rapidly or slowly progressive?

A

Rapidly

86
Q

Are footpads typically involved in EBA?

A

Yes- sloughing seen

87
Q

What is the primary inflammatory infiltrate in EBA?

A

Neutrophils

88
Q

In what layer of the BMZ would you find anchoring filaments?

A

Lamina lucida

89
Q

What is the major target in dystrophic epidermolysis bullosa?

A

Collagen VII (COL7A1 gene)

90
Q

What is the most common AISBD in humans?

A

Bullous pemphigoid

91
Q

Where is the salt split for EBA?

A

Dermal side (both sides rare)

92
Q

What is the pathogenesis of acquired junctional EB?

A

IgG autoantibodies to laminin 332

93
Q

Where is the salt split for acquired junctional EB?

A

Dermal side or both

94
Q

Where is the salt split for linear IgA bullous disease?

A

epidermal

95
Q

When does the onset of epidermolysis bullosa simplex occur?

A

immediately after birth

96
Q

Where do the blisters occur in junctional EB?

A

within the lamina lucida

97
Q

Where do blisters occur in dystrophic epidermolysis bullosa?

A

Beneath lamina densa

98
Q

What is the mutation in dystrophic epidermolysis bullosa?

A

COL7A1 (collagen VII)

99
Q

What is the inheritance pattern for dystrophic epidermolysis bullosa in cats, dogs, and ruminants?

A

Autosomal recessive (humans also have a dominant form)

100
Q

What is the PAS staining pattern for dystrophic EB?

A

BMZ attached to roof of cleft

101
Q

What AISBD targets intermediate keratin filaments?

A

EB simplex

102
Q

What AISBD targets plectin?

A

EB simplex (in Eurasier dogs and one horse case)

103
Q

Where is integrin alpha6beta4 found in the BMZ?

A

Intracellular in the outer plaque AND extracellularly as part of lamina lucida

104
Q

What AISBD occurs when integrin alpha6beta4 is affected?

A

Junctional EB

105
Q

What congenital AISBD could result from targeting of collagen XVII?

A

Junctional EB (reported in 2 cats)

106
Q

What autoimmune AISBDs could result from targeting of collagen XVII?

A

BP, MMP, linear IgA

107
Q

Is laminin 332 located intracellularly or extracellularly?

A

Extracellularly

108
Q

What congenital AISBD might result from targeting of laminin 332?

A

Junctional EB

109
Q

What autoimmune AISBDs might result from targeting of laminin 332?

A

MMP, acquired JEB, mixed AISBD

110
Q

What organ system is typically affected in congenital disorders affecting collagen IV?

A

Kidney (Samoyed, English Cocker Spaniel)

111
Q

What diseases in vet med are associated with targeting of nidogens and perlecan?

A

none

112
Q

What part of the BMZ loops around dermal collagen and helps anchor the epidermis to the dermis?

A

Collagen VII

113
Q

What congenital AISBD might result from targeting of collagen VII?

A

Dystrophic EB

114
Q

What autoimmune AISBDs might result from targeting of collagen VII?

A

EBA
type I bullous SLE

115
Q

What breed is predisposed to EBA?

A

Great Dane

116
Q

When doing salt split technique for an AISBD, where is the split occurring?

A

Through the lamina lucida (bottom is just lamina densa and dermis)

117
Q

Are the blisters seen in AISBDs commonly tense or fragile?

A

Tense

118
Q

How does BP in horses differ from that of other species?

A

More oral cavity involvement (haired skin predominance for other animals)

119
Q

How does BP in pigs differ from that of other species?

A

Usually no mucosal involvement

120
Q

What is the name of MMP in humans?

A

cicatricial pemphigoid

121
Q

Are the larynx and esophagus usually involved in canine MMP?

A

No (they are in humans)

122
Q

What has been the most helpful treatment for MMP?

A

Tetracycline/niacinamide

123
Q

What is the main target for EBA?

A

Collagen VII (NC1 doman)

124
Q

Are cats reported to be affected with EBA?

A

No (only dogs and humans)

125
Q

Is the oral cavity involved in EBA?

A

Yes, always

126
Q

What breeds are predisposed to JEB?

A

Australian Shepherds, GSP

127
Q

What is the typical age of onset of JEB (not JEBA)?

A

Within a few weeks of birth (not right at birth)

128
Q

What are the most common body regions affected with JEBA?

A

Pinnae, oral cavity

129
Q

What AISBD in humans has a “string of pearls” clinical appearance?

A

Linear IgA disease

130
Q

What are the autoimmune targets in mixed AISBD?

A

laminin 332 and collagen VII

131
Q

What is the recommended treatment for pemphigoid gestationis?

A

Ovariohysterectomy–> complete remission within a few months

132
Q

Is dystrophic EB congenital or acquired?

A

Congenital

133
Q

Is the inheritance of dystrophic EB recessive or dominant in animals?

A

Recessive (humans also have a dominant form)

134
Q

What are the two subtypes of human EBA?

A

Mechanobullous (“classic”)
Inflammatory

135
Q

What subtype of human EBA does the canine form most closely represent?

A

Inflammatory

136
Q

What 3 clinical features help differentiate EBA from other AISBD?

A

Age of onset (young)
Oral cavity, glabrous skin, foot pads involved
More severe systemic CS

137
Q

What is the most common treatment for canine MMP?

A

Tetracycline + niacinamide

138
Q

What histopath stain is used to highlight the basement membrane?

A

PAS

139
Q

Identify the structures of the basement membrane zone

A
140
Q

What layer of the BMZ is an artifact of tissue processing?

A

Lamina lucida

141
Q

What do intermediate filaments bind to within the hemidesmosome?

A

Plectin
BPAG1e

142
Q

What hemidesmosome component is one of the earliest seen as the hemidesmosome develops?

A

CD151

143
Q

What BMZ components does the alpha6 subunit of integrin alpha6beta4 interact with?

A

CD151
collagen XVII

144
Q

What is the main component of anchoring filaments?

A

Laminin 332

145
Q

What structures make up the lamina densa?

A

Collagen IV
Laminin-332
Nidogen
Perlecan
Collagen VII

146
Q

What BMZ structure resembles a hockey stick?

A

Collagen IV

147
Q

Is the sublamina densa part of the epidermis or part of the dermis?

A

Dermis

148
Q

How do type II hemisdesmosomes differ from type I?

A

Type II found only in fetal skin
Type II contain only integrin alpha6beta4 and plectin

149
Q

What components of the BMZ have been associated with tumor progression?

A

integrin alpha6beta4
laminin-332
CD151
Collagen VII

150
Q

What is the staining pattern on salt-split mucosa for MMP?

A

Epidermal (most cases)
Dermal
Both

151
Q

True or false: most cases of canine MMP went into remission with glucocorticoid monotherapy

A

False - tetracycline + niacinamide work best
GC alone are least successful in dz control

152
Q

What test can be done to differentiate MMP from EBA?

A

PAS - stains floor/dermal side in MMP

153
Q

What would the expected PAS staining pattern be for canine EBA?

A

Positive staining on roof/epidermal side

154
Q

What would the expected salt-split staining pattern be for canine EBA?

A

Positive on the floor/dermal side

155
Q

True or false: Systemic clinical signs are uncommonly seen in canine EBA

A

False - systemic signs are common

156
Q

What species have been reported to be affected by EBA?

A

Dogs only

157
Q

Is bullous pemphigoid primarily a disease of haired or non-haired skin?

A

Haired skin (exception: horses)

158
Q

What is the PAS staining pattern for BP?

A

Stains floor/dermal side

159
Q

What is the salt-split staining pattern for BP?

A

Roof/epidermal side

160
Q

How can you differentiate canine EBA from JEBA?

A

PAS stain: JEBA has floor/dermal side staining

161
Q

What is the salt-split staining pattern for JEBA?

A

Dermal or both

162
Q

What are the targets of linear IgA disease?

A

cleavage products of collagen XVII

163
Q

What AISBD exhibits a biphasic age distribution in humans?

A

Linear IgA disease

164
Q

What is the salt-split staining pattern for linear IgA disease?

A

Roof/epidermal side

165
Q

What is the PAS staining pattern for pemphigoid gestationis?

A

Floor/dermal side

166
Q

What is the salt-split staining pattern for pemphigoid gestationis?

A

Roof/epidermal side

167
Q

What is the target of pemphigoid gestationis?

A

Collagen XVII

168
Q

What dog breed has been reported in pemphigoid gestationis?

A

Tibetan spaniel

169
Q

What is the salt-split staining pattern for type I bullous SLE?

A

Floor/dermal side

170
Q

What is the PAS staining pattern for type I bullous SLE?

A

Roof/epidermal side

171
Q

What AISBD can be diagnosed solely on clinical and histopathologic features?

A

MMP (due to its restriction to mucous membranes)

172
Q

What AISBD has been shown to have “rowing” of neutrophils along the BMZ?

A

EBA

173
Q

What AISBD typically lacks inflammation on histopath?

A

MMP (though many AISBDs are not highly inflammatory)

174
Q

What non-steroidal immunosuppressive drug can be particularly helpful for tx of EBA?

A

Colchicine (because of higher proportion of neutrophils seen in this AISBD)