34- other vesiculobullous diseases

Question 1

What is the epidemiology of bullous diabeticorum?

Answer 1

• occurs in patients with either type 1 or type 2 diabetes. 2:1 male to female ratio
• usually aged 55 years
• usually in long standing diabetes but on occasions can be the first sign.

Question 2

What is the pathogenesis of bullous diabeticorum?

Answer 2

• eitology not well known
• possibly related to trauma and microaniopathy of dieabetes.
• possibly a reduced threshold for blistering

Question 3

what are the clinical features of bullous diabeticorum?

Answer 3

• sudden onset of spontaneous bland vesicles and bullae on distal extremities.
• perception that these may have “appeared overnight” with no trauma.
• mild burning sensation
• mostly occur on the feet, lower legs, hands and forearms.

Question 4

what are the histopathological findings of bullous diabeticorum?

Answer 4

• subepidermal cleavage

- there can be intraepidermal cleavage in older lesions.

Question 5

what are the differential diagnosis of bullous diabeticorum?

Answer 5

• bullous drug eruption
• porphyria cutanea tarda
• pseudoporphyria associated with dialysis/medications (usually bullae are less than 1 cm).

Question 6

what are coma bullae and how do they present?

Answer 6

These are blisters that develop wihtin 48 -72 hours of loss of consciousness. They occur primarily at pressure sites and are associated with barbituarate overdose/ coma due to meds/infections/metabolic disorbances.

Lesions appear at sites that had maximum pressure when unconcious. Start off as erythematous plaques or patches and turn violaceous.

Question 7

what are additional complications that can be seen in patients with coma bullae?

Answer 7

• non-traumatic rhabdomyolysis,

- compression neuropathy.

Question 8

what are the differential characteristics of each of these blistering disorders: bullous diabeticorum, coma blisters, friction blisters, bullous small vessel vasculitis, bullous drugneruptions, bullousinsect bites, delayed postburn-post graft blisters and edema blisters.

Discuss clinical features and histopathology findings for each.

Answer 8

see table 34.1 in Bolognia.

p469

Question 9

What is seen histologically in coma blisters? What is the characteristic finding?

Answer 9

• subepidermal blistering
• only a sparse inflammatory cell infiltrate. DIF usually negative.
• IgM and C3 can sometimes be found in the walls of dermal blood vessels.
• sweat gland necrosis is characteristic.

Question 10

what is the pathology of friction blisters?

what are the predisposing factors?

Answer 10

• due to frictional shearing forces in the epidermis when something rubs against the skins surface.
• the predisposing factors including: poorly fitting shoes, heat and sweating.

Question 11

what are the clinical features of friction blisters?

Answer 11

• These develop in areas with a thick stratum corneum (e.g soles, heels, palms). Most common on the feet.
• erythematous macules develop at sites of friction and then develop into blisters.

Question 12

What are the histopathological findings of friction blisters?

Answer 12

• intraepidemal blisters - split seen in the stratum spinosum (just below the stratum granulosum).
• deeper layers of the epidermis are normal.

Question 13

What are the differential diagnosis of friction blisters?

Answer 13

• epidermolysis bullosa (Weber-Cockayne)

- EBA

Question 14

Which patients are at risk of severe bullous insect bite reactions?

Answer 14

• children

- patients with chronic lymphocytic leukemia

Question 15

Which immunity type is involved in a bullous bite reaction

Answer 15

Both humoral and cell mediated immunity (I.e type I and Type IV)

Question 16

What is seen histologically on a bullous bite reaction?

Answer 16

• perivascular and periadnexal lymphocytic infiltrate with abundant eosinophils.
  Characteristic wedge shaped pattern.
• Flame figures can be seen.

Question 17

which bites are the most likely to cause blisters?

Answer 17

Flea bites.

Question 18

When do delayed postburn/post graft blisters occur?

Answer 18

These occur weeks to months after the initial healing of second-degree thermal burns, donor sites and recipient sites of split-thickness skin grafts.