A Challenging Cutaneous T-Cell Lymphoma.

Area of Science:

• Dermatology
• Oncology
• Hematopathology

Background:

• Cutaneous peripheral T-cell lymphomas not otherwise specified (CPTL-NOS) are rare neoplasms, comprising only 2% of all cutaneous peripheral T-cell lymphomas (CPTL).
• Existing literature on CPTL-NOS is limited, with few reported case series, underscoring the need for further clinical and pathological characterization.
• CPTL-NOS represents a phenotypically and prognostically heterogeneous group of CPTL that do not fit into well-defined subtypes.

Observation:

• A 64-year-old man presented with simultaneous plaque-like lesions and rapidly growing disseminated nodules across 80% of his skin surface over six months.
• The patient had no prior history of erythematous patches, plaques, rash, or pruritic lesions.
• Histopathology revealed dense, diffuse dermal infiltrates of medium-to-large atypical lymphoid cells with pleomorphic nuclei, lacking epidermotropism.

Findings:

• Immunohistochemistry demonstrated tumor cells positive for CD3, CD4, and CD5, with a loss of CD7, and negative for CD20, CD8, CD56, and other markers.
• The neoplastic cells exhibited a low proliferative fraction, with MIB-1 labeling less than 10%.
• The patient was diagnosed with primary CPTL-NOS based on these clinical and pathological findings.

Implications:

• Familiarity with rare CPTL-NOS is crucial for dermatopathologists and pathologists due to their typically aggressive behavior and unfavorable prognosis.
• This case underscores the importance of recognizing diverse presentations of CPTL-NOS for timely diagnosis and treatment planning.
• Further research into CPTL-NOS is warranted to improve understanding and therapeutic strategies for these rare lymphomas.