Superficial CD34 Positive Fibroblastic Tumour with Myxoid Stroma.

Superficial CD34 positive fibroblastic tumor is a rare low-grade neoplasm of the skin and subcutis with indolent behavior. This entity has been included in the current World Health Organisation (WHO) classification of soft tissue tumors. Pathological diagnosis can be challenging due to significant morphological overlap with other entities and the large spectrum of CD34 positive tumors. We report a case in a twenty-five male which showed characteristic diagnostic features, but in addition showed myxoid stroma. The presence of myxoid stroma has not been previously emphasized in this entity and broadens the histologic differential diagnosis significantly to include myxoid soft tissue tumors. A subset of these tumors harbor PRDM10 -rearrangements, but a defining molecular feature has not yet been described, highlighting the need for further molecular characterization of this potentially genetically heterogenous tumor. Awareness of this entity among surgeons and pathologists is important to prevent misclassification as an aggressive sarcoma and avoid over-treatment.