Orbital atypical lymphocytic panniculitis preceding conjunctival marginal zone lymphoma in the same patient with undifferentiated connective tissue disease: a case-based review.

The association between autoimmune diseases and lymphoproliferative disorders is well established. It is also recognized that the skin and deep subcutaneous tissue can be affected by lymphocytic infiltrates in autoimmune diseases, a hallmark of lupus erythematosus profundus or lupus panniculitis (LP). To present an unusual lymphoproliferative disorder in a patient with undifferentiated connective tissue disease (UCTD). A 60-year-old female was diagnosed in 2019 with UCTD. Nearly two years later, clinical and laboratory signs of the disease subsided, but she developed mild ptosis of the right upper eyelid due to edema and increased lacrimation of the right eye. Histopathological findings were consistent with lymphocytic panniculitis. Five months later, the patient developed a hyperemic, slightly elevated conjunctiva at the superior temporal pole of the left eye, with prominent episcleral blood vessels. A diagnosis of conjunctival marginal zone B-cell non-Hodgkin lymphoma (NHL) was established. Clonality of the IgH gene in FR1 and FR2 regions was demonstrated in both lesions-lymphocytic panniculitis and lymphoma. Atypical lobular lymphocytic panniculitis (ALLP) is considered part of a spectrum of cutaneous T-cell lymphoid dyscrasias, with LP at one end and subcutaneous panniculitis-like T-cell lymphoma (SPTCL) at the other. Differentiating between LP, ALLP, and SPTCL can be challenging both clinically and histologically, yet it is crucial to determine whether lymphocytic panniculitis is a benign reactive condition or a lymphoproliferative process. While clonal restriction is typically found in ALLP and SPTCL, it is generally absent in LP. In our case, lobular panniculitis exhibited clonal B-cell restriction, supporting a diagnosis of atypical B-cell lymphocytic panniculitis. This case underscores the importance of recognizing atypical B-cell lymphocytic panniculitis as a potential precursor to B-cell NHL. Patients with autoimmune diseases and lymphocytic panniculitis-whether of T- or B-cell phenotype-should be carefully monitored for signs of lymphoproliferative transformation.