case_images: PMC10034281_01
case_images: Erythematous and edematous papules and plaques with slight targetoid
  appearance on the dorsal and lateral upper arms (a and b) and legs (c).
  There was absence of vesicles or bullae and mucocutaneous involvement.
case_images: 10.1177_2050313X231160926-fig1.jpg
case_images: PMC10034281_01_10.1177_2050313X231160926-fig1.jpg
case_images: fig1-2050313X231160926
case_images: On the upper arms and thighs, there were pink erythematous and oedematous papules and plaques with slight targetoid appearance (Figure 1) despite being previously started on oral prednisone 70 mg/day 10 days prior to her initial assessment.
case_images: Histopathology with hematoxylin and eosin staining revealed non-specific but
  did reveal mixed infiltrate with numerous eosinophils within the superficial
  dermis and presence of basal vacuolar changes without separation of the
  epidermis from the dermis at (a) 4x and (b) 20x magnification. Direct
  immunofluorescence (DIF) was obtained and demonstrated linear staining
  showing (c) linear IgG and (d) linear C3 at the dermal-epidermal
  junction.
case_images: 10.1177_2050313X231160926-fig2.jpg
case_images: PMC10034281_01_10.1177_2050313X231160926-fig2.jpg
case_images: fig2-2050313X231160926
case_images: A skin biopsy of a representative urticoid papule for histopathology with hematoxylin and eosin staining (H&E) as well as perilesional tissue for direct immunofluorescence (DIF) was obtained and was consistent with BP (Figure 2).
case_images: (a) and (b) Numerous tense uniloculated bullae on background of erythema. (c)
  There were persistent bullae as well as the development of new bullae on
  follow-up examination, despite prednisone 50 mg per day for over
  6 weeks.
case_images: 10.1177_2050313X231160926-fig3.jpg
case_images: PMC10034281_01_10.1177_2050313X231160926-fig3.jpg
case_images: fig3-2050313X231160926
case_images: On re-examination, there were persistent urticoid papules and plaques as well as new tense, uniloculated bullae and scattered erosions with hemorrhagic crust on a background of erythema distributed diffusely to the upper arms and thighs, abdomen, upper chest, and neck (Figure 3(a) and (b)), and there were persistent and development new bullae noted despite prednisone 50 mg per day for 6 weeks (Figure 3(c)).
case_images: Resolving urticoid papules and plaques with few scant bullae and hemorrhagic
  crusts on the abdomen (a), arms (b and c), and legs (d) following
  upadacitinib 15 mg per day for 4 weeks.
case_images: 10.1177_2050313X231160926-fig4.jpg
case_images: PMC10034281_01_10.1177_2050313X231160926-fig4.jpg
case_images: fig4-2050313X231160926
case_images: The patient did demonstrate initial response to upadacitinib with resolving urticoid eruption, scattered healing erosions, and no active bullae or mucosal progression on re-evaluation at 4 weeks (Figure 4).