Non-Neoplastic Dermatopathology

L UPUS PANNICULITIS VS SUBCUTANEOUS PANNICULITIS-LIKE T-CELL LYMPHOMA

5.7

Subcutaneous Panniculitis-Like T-Cell Lymphoma Occurs in both children and adults with a wide range of ages. Average age of presentation typically in the fourth decade.

Lupus Panniculitis

Age

Variable age of presentation but typically between 30 and 60 years of age. More frequent in women. Most commonly involves upper arms and shoulders but can involve trunk, buttocks, chest, face, and scalp. Autoimmune disorder caused by failure of the mechanisms that maintain self-tolerance. Genetic and environmental factors, including ultraviolet radiation, sex hormones, and medications, contribute to the pathogenesis. Autoantibodies, directed toward a variety of nuclear proteins, mediate tissue injury. Tender, deep-seated, indurated, erythematous nodules or plaques. Lesions may be solitary or arise in crops involving multiple regions. 1. Variable superficial changes of hyperkeratosis, interface vacuolar degeneration, perivascular lymphocytic infiltrate, and dermal mucin deposition (Fig. 5.7.6) . In many cases, the epidermis and dermis are unremarkable. 2. Predominantly lobular infiltrate of small lymphocytes without cytologic atypia (Figs. 5.7.1-5.7.3) . May have associated germinal center formation and plasma cells. Lymphocytes do not show rimming of adipocytes. 3. Lymphocytic vasculopathy with infiltration of subcutaneous vessel walls by lymphocytes, endothelial swelling, and erythrocyte extravasation (Fig. 5.7.4) . 4. Hyaline sclerosis and myxoid change of collagen of deep dermis and subcutaneous septa (Figs. 5.7.1 and 5.7.5) . 5. Lipomembranous fat necrosis occasionally involving subcutaneous fat lobules.

Location

Extremities and trunk primarily.

Etiology

Primary cutaneous lymphoma composed of neoplastic cytotoxic alpha-beta T-cell lymphocytes that migrate to the subcutaneous adipose tissue.

Presentation

Multiple, painless nodules or indurated plaques with dull erythematous surface. Individuals, especially those with concomitant hemophagocytic syndrome, may have associated fever, chills, myalgias, weight loss, and cytopenias. 1. May have epidermal vacuolar interface change and mucin deposition, but less commonly than lupus panniculitis. Generally, the overlying epidermis and dermis are unremarkable. 2. Subcutaneous lobular lymphocytic infiltrate that spares the septa (Fig. 5.7.7) . 3. Neoplastic lymphocytes are enlarged and have hyperchromatic nuclei with irregular nuclear contours (Figs. 5.7.9 and 5.7.10) . Plasma cells are rare, and germinal center formation is not present.

Histology

4. Atypical lymphocytes rim individual fat cells, and there are associated histiocytes with karyorrhectic debris (“bean bag cells”) (Figs. 5.7.8 - 5.7.10) . Copyright © Wolters Kluwer, Inc. Unauthorized reproduction of the content is prohibited. 2023

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