1. ¹Department of Dermatology and Allergology, Helsinki University Central Hospital, University of Helsinki, Helsinki, Finland
2. ²Division of Oncogenomics, Department of Pathology, University of Regensburg, Regensburg, Germany
3. ³Department of Medical Genetics, University of Helsinki, Helsinki, Finland
4. ⁴Department of Oncology, Helsinki University Central Hospital, Helsinki, Finland
5. ⁵Department of Internal Medicine, Helsinki University Central Hospital, Helsinki, Finland

Correspondence: Dr Sonja Hahtola, Department of Dermatology and Allergology, Helsinki University Hospital, Skin and Allergy Hospital, PO Box 160, 00029 HUS Helsinki, Finland. E-mail: sonja.hahtola@helsinki.fi

Received 29 June 2007; Revised 7 October 2007; Accepted 12 November 2007; Published online 13 March 2008.

Abstract

Subcutaneous panniculitis-like T-cell lymphomas (SPTLs) represent a rare, difficult-to-diagnose, and poorly characterized subtype of cutaneous T-cell lymphomas (CTCLs) affecting younger people more than the other CTCL forms. We performed a thorough clinical, immunohistological, and molecular analysis of nine Finnish SPTL patients. Specifically, we performed single-cell comparative genomic hybridization (CGH) from laser microdissected, morphologically malignant SPTL cells, as well as loss of heterozygosity (LOH) and fluorescence in situ hybridization (FISH) analysis for the NAV3 (neuron navigator 3) gene. CGH revealed large numbers of DNA copy number changes, the most common of which were losses of chromosomes 1pter, 2pter, 10qter, 11qter, 12qter, 16, 19, 20, and 22 and gains of chromosomes 2q and 4q. Some of the DNA copy number aberrations in SPTL, such as loss of 10q, 17p, and chromosome 19, overlap with those characteristic of common forms of CTCL (mycosis fungoides (MF) and Sezary syndrome (SS)), whereas 5q and 13q gains characterize SPTL. Allelic NAV3 aberrations (LOH or deletion by FISH), previously found in MF and SS, were identified in 44% of the SPTL samples. This study demonstrates that SPTL is also moleculocytogenetically a uniform entity of CTCL and supports the current World Health Organization–European Organization for Research and Treatment of Cancer (WHO–EORTC) classification defining SPTL as a subgroup of its own.