Interdigitating dendritic reticulum cell sarcoma: cytologic, histologic and immunocytochemical features.

Area of Science:

• Oncology
• Cytopathology
• Surgical Pathology

Background:

• Dendritic reticulum cell tumors are rare neoplasms with significant morphologic overlap with other malignancies.
• The fine-needle aspiration (FNA) cytologic features of these tumors are not well-established.
• Accurate diagnosis is crucial due to potential confusion with other cancers.

Observation:

• A 33-year-old woman presented with a rapidly growing right upper cervical mass and right-sided ptosis.
• FNA cytology revealed large, polygonal cells with high nuclear-cytoplasmic ratio, irregular nuclei, prominent nucleoli, and numerous mitoses.
• Immunocytochemistry showed focal CD45 and CD68 reactivity, with negativity for B-cell and T-cell markers, CD30, EMA, and cytokeratin.

Findings:

• Histologic examination of the biopsy demonstrated nodal effacement by pleomorphic neoplastic cells, some resembling Reed-Sternberg cells, with an infiltrate of small lymphocytes.
• Immunohistochemistry confirmed tumor cell expression of vimentin, S-100 protein, CD68, and MAC387.
• The tumor cells were negative for a broad panel of markers including lymphoid, histiocytic, and epithelial markers, supporting a histiocytic/dendritic lineage.

Implications:

• The study establishes the diagnostic utility of FNA cytology combined with immunocytochemistry for rare dendritic reticulum cell tumors.
• The findings aid in differentiating interdigitating dendritic reticulum cell sarcoma from other cervical malignancies.
• This case highlights the importance of comprehensive diagnostic workup for rare neoplasms presenting with overlapping features.