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Case 518 - Discussion

Uploaded: 2011-08-21, Updated: 2011-08-21

 

Primary Cutaneous Follicular Lymphoma

The Key Features

  • Medium to large centrocytes in follicular and/or diffuse growth patterns, no epidermal involvement.

  • BCL6+, CD10+, BCL2-, no BCL2 rearrangement.

  • Excellent prognosis, rarely extracutaneous involvement.

CLINICAL FEATURES

  • Germinal center B-cell origin.

  • Most common primary cutaneous B-cell lymphoma, 60% of all cases.

  • Mean age 51 years, M:F=1.5:1.

  • Characteristically as solitary or localized skin lesions of the scalp, forehead and trunk.

  • Usually localized to the skin, only ~10% disseminate to extracutaneous sites.

GROSS FINDINGS

  • Firm erythematous to violaceous plaques, nodules of variable sizes.

  • The surface is smooth and rarely ulcerated.

MICROSCOPIC FINDINGS

  • Perivascular and periadnexal, follicular and/or diffuse growth patterns.

  • Almost always sparing the epidermis.

  • Predominantly medium to large centrocytes and variable centroblasts.

  • The advanced tumors may show monotonous large centrocytes and multilobated cells and rarely spindle cells.

DIFFERENTIAL DIAGNOSES

  • ALCL: more pleomorphic with hallmark cells. T cell origin. Primary cutaneous ALCL usually CD30+ and ALK-.

  • DLBCL or DLBCL transformed from classic FL: more aggressive. The CD10+/BCL6+ DLBCL is GCB type and is usually also BCL2 positive.

  • Primary cutaneous DLBCL, leg type: 90% involving leg, lack of CD21+ FDC meshwork in tumor cell, mostly BCL2+ BCL6+CD10-.

  • Lymphomatoid papulosis: self-healing, CD4 T-cell origin, highly pleomorphic cells in an inflammatory background, CD30+ in type B.

IMMUNOHISTOCHEMISTRY AND SPECIAL STAINS

  • CD20+, CD79a+

  • BCL6 constantly positive, CD10 positive in follicular growth pattern and negative in diffuse pattern.

  • BCL2 mostly negative.

CYTOGENETIC STUDIES

  • No BCL2 rearrangement in most cases.

TREATMENT AND PROGNOSIS

  • Excellent prognosis, 5-year survival ~95%, regardless of growth patterns, number of blasts, t(14;18) status and localized or multifocal lesions.

REFERENCES

  • Swerdlow, S.H., Campo, E., Harris, N.L., Jaffe, E.S., Pileri, S.A., Stein, H., Thiele, J., Vardiman, J.W. WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues, Fourth Edition. 2008.

  • Rein Willemze, Elaine S. Jaffe, Guš nter Burg, Lorenzo Cerroni, Emilio Berti, Steven H. Swerdlow, Elisabeth Ralfkiaer, Sergio Chimenti, JoseŽ L. Diaz-Perez, Lyn M. Duncan, Florent Grange, Nancy Lee Harris, Werner Kempf, Helmut Kerl, Michael Kurrer, Robert Knobler, Nicola Pimpinelli, Christian Sander, Marco Santucci, Wolfram Sterry, Maarten H. Vermeer, Janine Wechsler, Sean Whittaker, and Chris J. L. M. Meijer. WHO-EORTC classification for cutaneous lymphomas. Blood. 2005;105:3768-3785.