Dermatofibrosarcoma Protuberans in 3 Patients with ADA-SCID

Dermatofibrosarcoma protuberans (DFSP) is a rare malignant skin tumor with characteristic cytogenetic findings (t(17;22)(q22;q13)) resulting in a fusion COL1A-PDGFB gene. Here we report an association between DFSP and Adenosine Deaminase Deficient Severe Combined Immunodeficiency (ADA-SCID), a rare congenital immunodeficiency syndrome. We observed DFSP in 3 ADA-SCID patients. The first patient is a 3.6-year-old boy who developed a 1.5 cm soft tissue mass on the right medial thigh. The second patient is a 2.4-year-old girl with 12 plaques (0.4– 0.8 cm) distributed on the trunk, thigh and lower extremities. The third patient is a 6-year-old boy with 5 depressed plaques ranging from 1–2 cm. The diagnosis in the first two patients was confirmed by immunohistochemistry (CD34 positive/Factor XIIIa negative) and demonstration of the COL1A1-PDGFB fusion by Fluorescent In Situ Hybridization (FISH). In the third patient, lesional tissue was positive for CD34 and negative for Factor XIIIa. FISH was inconclusive and further molecular analysis (RT-PCR) is ongoing. We came across two additional ADA-SCID patients in the literature who developed DFSP and we conclude therefore that this unique and unreported association between two rare disease entities merits further study. Importantly, our observations describe the first 2 cases presenting with multiple multicentric DFSPs. DFSP may be overlooked particularly in children who may present with an indolent plaque-like lesion mistaken as birthmark or benign vascular proliferation. DFSP in ADA-SCID may be caused by an unknown virus in the setting of defective immune surveillance. The search for a viral etiology is ongoing. Alternatively, the increased DNA breakage characteristic of ADA-SCID may play a role in the onset of this malignancy.