Crystal-deficient alveolar soft-part sarcoma with cutaneous involvement: a case report

Area of Science:

• Oncology
• Pathology
• Genetics

Background:

• Alveolar soft-part sarcoma (ASPS) is a rare soft tissue sarcoma.
• It typically affects deep tissues of the extremities.
• ASPS is characterized by the ASPL-TFE3 fusion gene resulting from der(17)t(X;17)(p11;q25) translocation.

Observation:

• Microscopically, ASPS shows alveolar growth with large cells containing characteristic PAS-positive rod-shaped crystals.
• Nuclear TFE3 protein immunoreactivity and large rectangular or rhomboid crystals are typical ultrastructural findings.
• This report details an unusual ASPS case with cutaneous involvement.

Findings:

• The presented ASPS case lacked typical large crystals, instead displaying prominent round granules.
• Molecular analysis confirmed the presence of the ASPL-TFE3 fusion transcript (type 2).
• This represents a rare instance of crystal-deficient ASPS with cutaneous manifestation.

Implications:

• This case expands the understanding of ASPS morphological variations.
• It underscores the importance of molecular genetic analysis for diagnosing atypical ASPS presentations.
• The findings may influence diagnostic criteria and treatment strategies for rare ASPS subtypes.