Compound clear cell sarcoma misdiagnosed as a Spitz nevus.

Area of Science:

• Oncology
• Dermatopathology
• Skeletal System Neoplasms

Background:

• Clear cell sarcoma (CCS) is a rare soft tissue sarcoma typically arising in deep connective tissues.
• CCS can be misdiagnosed as melanocytic lesions when primarily involving the dermis.
• Compound variants, with epidermal and soft tissue involvement, have not been previously documented.

Observation:

• A case of clear cell sarcoma (CCS) initially presenting as a benign-appearing lesion on the wrist of a young woman is described.
• The initial diagnosis was Spitz nevus, compound type.
• Twelve years later, metastatic disease to the axillary lymph node was diagnosed.

Findings:

• The metastatic tumor cells showed S100 protein immunoreactivity and a characteristic t(12;22) translocation.
• Fluorescence in situ hybridization confirmed EWSR1 rearrangement, supporting the diagnosis of metastatic CCS.
• Histopathological analysis revealed epidermal involvement by tumor cells, a novel observation for CCS.

Implications:

• This case demonstrates that clear cell sarcoma (CCS) can involve the epidermis, expanding its recognized morphological spectrum.
• Accurate diagnosis of CCS requires consideration of its potential epidermal involvement, especially in cases initially misdiagnosed.
• Understanding the full spectrum of CCS presentation is crucial for timely diagnosis and effective treatment of this rare malignancy.