Acute inflammatory dermatosis of the trunk

Vesicular bullous dermatosis

Dr. Emmanuelle Bourrat

Saint-Louis Hospital

The clinical case
Now it's your turn!
Co-prescription and advice

Clinical case presentation

This 15-year-old girl presented with suspected acute contact eczema of the upper trunk evolving for one week. She stopped using her perfume and cosmetics, removed her necklaces and changed her shampoo without any improvement. Likewise, the use of a potent topical corticosteroid and an antihistamine prescribed by her general practitioner had been ineffective.

This was a very fragile, pruritic papulovesicular eruption that, after scratching, progressed to small crusts and then desquamation. The lesions were located exclusively on the upper part of the anterior and posterior trunk and had a reticulated distribution.

Standard laboratory tests were normal apart from a slightly elevated CRP. A biopsy was performed to confirm a diagnosis suggested by the elementary lesion, the topography, the reticulated pattern and especially by a key element from the focused medical history.

Dermatose inflammtoire du tronc ketorash 1

Dermatose inflammtoire du tronc ketorash 2

Your turn

What is your diagnosis?

Select 1 answer(s) from the following choices:

Hailey-Hailey disease

Darier’s disease

Keto rash

Dermatitis herpetiformis

Wrong answer!

Good answer!

Diagnosis selected

The histological appearance combines parakeratosis, spongiosis, perivascular neutrophilic infiltrate and a few dyskeratotic keratinocytes, confirming the clinical diagnosis of keto rash complicating a recent very strict salad-based diet that excluded all carbohydrates.

The condition improved rapidly with simple dietary advice (reintroduction of starchy foods, bread, pasta, cereals) and without oral or topical treatment.

Ketone bodies are produced in various circumstances involving very low intake of slow-release carbohydrates (weight-loss diets, bariatric surgery, vomiting in early pregnancy, etc.). They are thought to have a proinflammatory effect on dermal vascularization and also a direct toxic effect on keratinocytes. The initial stage of reticular erosive dermatosis of the upper trunk is followed by a sequela phase with macular pigmentation of the same distribution.

Explanation of incorrect answers

Darier’s disease affects seborrheic areas and therefore commonly occurs on the upper trunk in the form of highly adherent keratotic papules. Histology mainly shows dyskeratosis.
Hailey-Hailey disease manifests itself in large folds as flaccid vesicles, painful erosions and fissures. The predominant histological feature is acantholysis.
Dermatitis herpetiformis is an autoimmune bullous dermatosis often associated with celiac disease and gluten intolerance. Clinically, it manifests as highly pruritic vesicles or blisters that quickly become excoriated, predominantly on the extensor surfaces of the elbows and knees and on the buttocks. The histology (and negative IF) in our patient did not support this diagnosis.

Treatment

If the reintroduction of complex carbohydrates is insufficient to achieve complete remission in the acute phase, treatment with tetracyclines or dapsone may be indicated.

Expert's message

Keto rash is a metabolic complication of ketogenic diets whose typical clinical and anatomical expression corresponds to prurigo pigmentosa, a dermatosis first described in 1971 mainly in Japanese women.

References:

^{Shaghayegh Shahrigharahkoshan. Ketogenic diet-induced prurigo pigmentosa: a rising association.}^{Int J Dermatol. 2022 Jul;61(7):779–782.}