title: Lymphocytic panniculitis: an algorithmic approach to lymphocytes in subcutaneous tissue.
abstract: The diagnosis of panniculitis is a relatively rare occurrence for many practising pathologists. The smaller subset of lymphocyte-predominant panniculitis is further complicated by the diagnostic consideration of T cell lymphoma involving the subcutaneous tissue, mimicking inflammatory causes of panniculitis. Accurate classification of the panniculitis is crucial to direct clinical management as treatment options may vary from non-medical therapy to immunosuppressive agents to aggressive chemotherapy. Many diseases show significant overlap in clinical and histological features, making the process of determining a specific diagnosis very challenging. However, with an adequate biopsy including skin and deep subcutaneous tissue, a collaborative effort between clinician and pathologist can often lead to a specific diagnosis. This review provides an algorithmic approach to the diagnosis of lymphocyte-predominant panniculitis, including entities of septal-predominant pattern panniculitis (erythema nodosum, deep necrobiosis lipoidica, morphea profunda and sclerosing panniculitis) and lobular-predominant pattern panniculitis (lupus erythematous panniculitis/lupus profundus, subcutaneous panniculitis-like T cell lymphoma, cutaneous γ-δ T cell lymphoma, Borrelia infection and cold panniculitis).
authors.affiliation: Department of Pathology, Royal Columbian Hospital, New Westminster, British Columbia, Canada Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Carolyn J
authors.initials: CJ
authors.lastname: Shiau
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Calgary and Calgary Laboratory Services, Calgary, Alberta, Canada.
authors.forename: Marie S
authors.initials: MS
authors.lastname: Abi Daoud
authors.affiliation: Department of Dermatology and Skin Science, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Se Mang
authors.initials: SM
authors.lastname: Wong
authors.affiliation: Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada Department of Dermatology and Skin Science, University of British Columbia, Vancouver, British Columbia, Canada Department of Pathology, Vancouver General Hospital, Vancouver, British Columbia, Canada.
authors.forename: Richard I
authors.initials: RI
authors.lastname: Crawford
mesh_terms: D000465:Algorithms; D003937:Diagnosis, Differential; D006801:Humans; D008214:Lymphocytes / Q000473:pathology; D016410:Lymphoma, T-Cell, Cutaneous / Q000473:pathology*; D015434:Panniculitis / Q000145:classification / Q000473:pathology*; D012867:Skin / Q000473:pathology; D012878:Skin Neoplasms / Q000473:pathology*; D040521:Subcutaneous Tissue / Q000473:pathology
keywords: CONNECTIVE TISSUE DISEASES; DERMATOPATHOLOGY; LUPUS; LYMPHOCYTES; LYMPHOMA