Morbidly Obese Man With Abdominal Wall Cellulitis

What’s the underlying cause of current cellulitis in this morbidly obese man?

 

A morbidly obese man (weight over 400 lb) with multiple medical comorbidities and a long history of extensive psoriasis is hospitalized for the third time for cellulitis of the abdominal wall. The skin of the wall is rock hard, with pebbly nodularity of the surface.

 

What underlying skin condition on the belly is predisposing to recurrent abdominal cellulitis?