Clinical Report: Young Adult with Malignant Melanocytic Neoplasm Lacking SMARCB1

Background

SMARCB1 (INI1)-deficient tumors are rare and aggressive neoplasms associated with significant diagnostic challenges due to their atypical presentations. The presence of melanocytic differentiation in these tumors is particularly uncommon, complicating their classification and management. Understanding these tumors is crucial for accurate diagnosis and treatment planning. [Citation needed]

Data Highlights

No numerical or trial data available in the source material, indicating a lack of quantitative analysis in the current report.

Key Findings

• A 21-year-old woman presented with left retro-orbital pain and visual impairment.
• The enucleated tumor showed a highly cellular malignant epithelioid neoplasm with marked cytologic atypia and focal melanocytic differentiation.
• Immunohistochemistry revealed complete loss of INI1 expression and a pathogenic SMARCB1 alteration.
• Histopathological examination confirmed vertebral metastases with similar tumor characteristics.
• Despite multimodal treatment, the patient experienced progressive disease and died three years post-diagnosis.

Clinical Implications

Integrated histopathologic and molecular assessments are important in diagnosing SMARCB1-deficient tumors. Clinicians should be aware of atypical presentations and the aggressive nature of these neoplasms.

Conclusion

This case expands the understanding of SMARCB1-deficient tumors and highlights the need for careful diagnostic evaluation in cases of melanocytic differentiation.

Related Resources & Content

1. Cyrta et al., PMC, 2025 -- SMARCB1-deficient malignant melanocytic uveal tumours: a new neural crest-derived tumour entity with SMARCB1-related germline predisposition
2. ESMO-EURACAN, 2026 -- Uveal melanoma: Clinical Practice Guideline for diagnosis, treatment and follow-up
3. Frontiers in Oncology — Case Report: Synaptophysin-positive SMARCA4-deficient undifferentiated thoracic tumour: a diagnostic pitfall with therapeutic implications
4. Frontiers in Oncology — Case Report: Primary sporadic intramedullary malignant peripheral nerve sheath tumor with intracranial extension and a subpial nodule suggestive of early dissemination
5. Frontiers in Medicine — Case Report: Thoracic SMARCA4-deficient undifferentiated tumor with extraocular muscle metastasis: a rare case hidden in diplopia
6. Journal of Neuro-Oncology — Emergence of Neurometastatic Merkel Cell Carcinoma: A Case Series and Review of Existing Literature
7. SMARCB1 ‐deficient malignant melanocytic uveal tumours: a new neural crest‐derived tumour entity with SMARCB1 ‐related germline predisposition - PMC
8. Uveal melanoma: ESMO-EURACAN Clinical Practice Guideline for diagnosis, treatment and follow-up†
9. Metastatic Uveal Melanoma Surveillance: A Delphi Panel Consensus