Expression of fibrogenic cytokines in desmoplastic malignant melanoma

Desmoplastic malignant melanoma (DMM) consists of amelanotic spindle-shaped melanoma cells and is accompanied by desmoplasia with fibrous stromata. It has a strong tendency for local infiltrative growth and recurrence and a propensity for neurotropism. It is not yet known which cytokine is responsible for the desmoplasia in DMM. In the present study, we investigated the roles of several fibrogenic cytokines and cytokine receptors in DMM: basic fibroblast growth factor (bFGF), connective tissue growth factor (CTGF), transforming growth factor-beta, platelet-derived growth factor (PDGF) and PDGF receptors. Immunostaining and in situ hybridization were conducted in four cases of DMM and four cases of amelanotic malignant melanoma (AMM) as negative controls for desmoplasia. PDGF-beta receptor, bFGF and CTGF were intensely expressed in the DMM specimens in comparison with the AMM specimens. The reaction of PDGF-B ligand and CTGF to PDGF-beta receptor, in addition to the expression of bFGF, may contribute to the desmoplasia in DMM.