Clinical boundaries in adult cases of large B cell lymphoma with IRF4 rearrangement.

AIMS: Large B-cell lymphoma with IRF4 rearrangement (LBCL-IRF4) is a recently described entity included in the revised 4th edition of the WHO Classification of Haematolymphoid Tumours (2017). Here we highlight the difficulties in classification of those cases which arise in adult patients with unusual clinical features. RESULTS: We present three cases with morphological and immunohistochemical features consistent with large B-cell lymphoma arising in adult patients, which were found to have isolated IRF4 rearrangements on FISH analysis. Each patient presented with advanced-stage disease and had a history of immunosuppression; clinical features that are not typical of LBCL-IRF4 and which make the distinction from DLBCL, not otherwise specified (NOS) challenging. CONCLUSION: We propose that the clinical boundaries of LBCL-IRF4 arising in adult patients need further delineation to allow distinction from true cases of DLBCL, NOS.

Migrating Polyarthritis as a Feature of Occult Malignancy: 2 Case Reports and a Review of the Literature.

Malignant disease may be associated with a wide variety of musculoskeletal syndromes. Rarely the musculoskeletal system can be indirectly affected by paraneoplastic phenomena, such as carcinomatous polyarthritis (CP). The differential diagnosis for CP is broad and is often a diagnosis of exclusion. CP often presents similarly to other forms of inflammatory arthritis, and a detailed history and physical examination can often distinguish CP from other more common causes of polyarticular arthritis. However serological tests such as rheumatoid factor (RF) and anti-citrullinated peptide (anti-CCP) antibody positivity, while rare, can be misleading. Clinical awareness and suspicion are paramount in achieving an accurate diagnosis and early detection of an occult neoplasm is critical for prompt management and therapy. We report two cases presenting with this unique clinical phenotype associated with paraneoplastic polyarthropathy and review the literature.