Inclusion Criteria (all subjects)

   - Psoriasis vulgaris on trunk and/or limbs affecting at least 2% BSA.

   - Psoriasis vulgaris on the scalp affecting at least 10% of total scalp area.

   - A total psoriatic involvement on trunk, limbs and scalp not exceeding 30% BSA.

   - PGA score of at least mild on trunk and/or limbs at SV1, SV2 and V1.

   - PGA score of at least mild on scalp at SV1, SV2 and V1.

   - A serum albumin-corrected calcium below the upper reference limit at SV2.

Inclusion Criteria (for subjects performing HPA axis assessment)

   - Psoriasis vulgaris on trunk and/or limbs affecting at least 10% BSA.

   - Psoriasis vulgaris on the scalp affecting at least 20% of total scalp area.

   - PGA score of at least moderate on trunk and limbs at SV1, SV2 and V1.

   - PGA score of at least moderate on scalp at SV1, SV2 and V1.

   - Normal HPA axis function at SV2 (serum cortisol concentration above 5 mcg/dl before
   ACTH challenge and serum cortisol concentration above 18 mcg/dl 30 minutes after ACTH
   challenge).

Exclusion Criteria (all subjects):

   - A history of hypersensitivity to any component of LEO 90100.

   - Systemic treatment with biological therapies (marketed or not marketed), with a
   possible effect on scalp and/or body psoriasis within the following time period prior
   to V1 and during the trial:

      1. etanercept - within 4 weeks prior to V1

      2. adalimumab, infliximab - within 2 months prior to V1

      3. ustekinumab - within 4 months prior to V1

      4. experimental products - within 4 weeks/5 half-lives (whichever is longer) prior
      to V1

   - Systemic treatment with therapies other than biologicals, with a possible effect on
   scalp and/or body psoriasis (e.g. methotrexate, retinoids, immunosuppressants) within
   4 weeks prior to V1 or during the trial.

   - PUVA therapy within 4 weeks prior to V1.

   - UVB therapy within 2 weeks prior to V1 or during the trial.

Exclusion Criteria (for subjects performing HPA axis assessment):

   - A history of serious allergy, allergic asthma or serious allergic skin rash.

   - Known or suspected hypersensitivity to any component of CORTROSYN® (including
   ACTH/cosyntropin/tetracosactide)

   - Systemic treatment with corticosteroids (including inhaled and nasal steroids) within
   12 weeks prior to SV2 or during the trial.

   - Oestrogen therapy (including contraceptives) or any other medication known to affect
   cortisol levels or HPA axis integrity within 4 weeks prior to SV2 or during the trial.