Intrasinusoidal ALK-positive anaplastic large cell lymphoma.

Area of Science:

• Hematopathology
• Oncology
• Lymphoma Research

Background:

• Anaplastic large cell lymphoma (ALCL), particularly ALK-positive subtypes, can involve lymph node sinuses.
• Exclusive intrasinusoidal infiltration of lymph nodes by ALCL is an exceptionally rare presentation.

Purpose of the Study:

• To describe a unique case of ALK-positive ALCL presenting with isolated intrasinusoidal infiltration of an inguinal lymph node.
• To highlight the diagnostic challenges posed by this rare pattern, which can mimic metastatic carcinoma.
• To emphasize the importance of recognizing this presentation for appropriate management.

Main Methods:

• Case report of a 39-year-old woman with stage I inguinal lymphadenopathy.
• Histopathological examination of the lymph node, including immunohistochemistry for CD30 and ALK.
• Clinical correlation and diagnostic workup.

Main Results:

• Massive intrasinusoidal infiltration by CD30- and ALK-positive atypical cells was observed.
• Lymph node architecture was preserved despite extensive infiltration.
• The pattern mimicked metastatic carcinoma, posing a diagnostic challenge.

Conclusions:

• Exclusive intrasinusoidal infiltration by ALK-positive ALCL is a rare but critical differential diagnosis in cases of lymphadenopathy.
• Prompt recognition is essential as ALK-positive ALCL generally responds well to therapy.
• Further research is needed to elucidate the clinical and prognostic significance of this specific presentation.