Expression of embryonic stem cell markers SOX2 and nestin in dermatofibrosarcoma protuberans and dermatofibroma

Dermatofibrosarcoma protuberans (DFSP) was recently proposed to originate from a nestin-positive stem cell. In postnatal skin, nestin and another embryonic stem cell marker, SOX2, display a similar expression pattern with immunoreactivity in the hair follicle papilla and scattered cells of the perifollicular connective tissue sheath. The distribution pattern differs only in early embryogenesis, when nestin but not SOX2 is also expressed throughout the entire interfollicular dermis. We speculated that DFSP would not only be nestin-positive but also SOX2-positive.

With appropriately reacting external and internal controls, we examined 24 examples of DFSP for SOX2 and nestin. For comparison, we included 10 dermatofibromas (DFs).

All 24 cases of DFSP were immunoreactive for nestin but negative for SOX2. The DFs were both nestin-negative and SOX2-negative.

The observed staining pattern may indicate that DFSP derives from a subtype of nestin-immunoreactive mesenchymal stem cell that is different from the nestin- and SOX2-positive cell population of the perifollicular mesenchyme. Alternatively, nestin expression in DFSP may represent a recapitulation of the staining pattern in early embryogenesis without necessarily indicating that the nestin-positive cells represent stem cells. Also, DFSP may derive from hair follicle-associated mesenchymal stem cells that have lost their SOX2 expression.