Sunitinib efficacy in the treatment of metastatic skin adnexal carcinomas: report of two patients with hidradenocarcinoma and trichoblastic carcinoma.

Background: Adnexal carcinomas are rare and diverse cutaneous tumours. They are locally aggressive and have the potential for distant metastasis. Metastatic adnexal carcinomas are very resistant to conventional chemotherapies. Sunitinib, an oral tyrosine kinase inhibitor, is reportedly effective for the treatment of various solid cancers. Its use in adnexal carcinomas has never been reported.
Observations: The first patient had metastatic clear cell hidradenocarcinoma and was stabilized over 8 months with sunitinib, before she relapsed. The second patient had a metastatic malignant hair follicle tumour (trichoblastic carcinoma) and achieved a partial remission with sunitinib, and disease stabilized after 10 months. Dynamic contrast-enhanced ultrasound (DCE-US) performed to evaluate tumour vascularization during treatment depicted a dramatic and early decrease in the tumour blood volume.
Conclusions: Sunitinib was effective in controlling the disease in our two patients. DCE-US using linear raw data may have an early predictive value for tumour response to sunitinib. Further studies involving larger cohorts of patients are warranted in order to confirm the efficacy of sunitinib in these rare tumours.