GlaxoSmithKline‘s (NYSE: GSK) dermatology subsidiary Stiefel is building up its drug pipeline with a deal in principal to acquire a skin treatment candidate from Welichem Biotech (TSX:WBI).

Stiefel gets development and commercialization rights to anti-inflammatory compound WBI-1001, which is currently in phase 2 clinical development for treating psoriasis and atopic dermatitis, a type of eczema. The deal still needs approval by Welichem shareholders.

If Wilichem shareholders give their O.K., the Vancouver, British Columbia company will get an up front payment of about $33.9 million.

The company could receive additional milestone payments if WBI-1001 hits development milestones. Stiefel, based in Research Triangle Park, gets global rights to the compound outside of China, Taiwan, Macao and Hong Kong. But Stiefel also has a conditional right to acquire development and commercialization rights to those markets collectively. Exercising that right could trigger an additional payment of about $14.5 million to Wilichem.

The psoriasis market is large and growing. Psoriasis products totaled $4.5 billion in 2011 sales led by Amgen‘s (NASDAQ:AMGN) Enbrel, according to Research and Markets. Psoriasis sales are projected to reach $5.5 billion by 2020.

WBI-1001, Welichem’s lead drug candidate, was discovered with the company’s proprietary drug discovery technology platform. The non-steroidal, topical anti-inflammatory drug candidate is being studied to treat mild to moderate psoriasis and moderate to severe atopic dermatitis. The company’s drug pipeline focuses on autoimmune and inflammatory disorders and cancers. Welichem’s cancer treatment candidate WBI-2100 is still in preclinical studies