Subcutaneous (panniculitis-like) T-cell lymphoma, STCL

Definition

A cytotoxic T-cell lymphoma involving subcutaneous tissue, composed of tumour cells of varying size and often showing marked necrosis and karyorrhexis.

Synonyms

Epidemiology

Rare, representing <1% of all non-Hodgkin lymphomas. There is a broad age range, which includes children.

Clinical features

Presentation is with multiple tender skin-coloured or erythematous subcutaneous nodules, most often on the lower extremities. Large nodules may be necrotic. Some patients develop a haemophagocytic syndrome, pancytopenia, fever, myalgia and hepatosplenomegaly. There is not usually lymphadenopathy.

Histopathology

At an early stage, the infiltrate may appear deceptively benign. The infiltrate extends throughout the subcutis. Neoplastic cells range from small with round nuclei to large with hyperchromatic nuclei. Rimming of fat cells by the neoplastic cells is characteristic. A reactive histiocytic component is common, with vacuolation of the histiocytes due to ingestion of lipid. Conspicuous mitoses, vascular invasion, karyorrhexis and necrosis may be seen. The dermis is usually spared, except in gd-positive cases. Phagocytosis of erythrocytes be non-neoplastic macrophages is a harbinger of the haemophagocytic syndrome1. Angioinvasion and destruction are associated with an NK immunophenotype1.

Immunohistochemistry

CD1a
CD2	positive1
CD3	positive
CD4	negative, except in CD4+ variants1
CD5
CD7
CD8	usually positive, unless gd-positive
CD11b
CD16
CD20	negative1
CD25	positive in 60% of cases1
CD30	positive in 40% of cases1
CD43	positive1
CD45	positive1
CD45RO	positive1
CD56	positive if gd-positive
CD57	negative except in NK variant1
TdT
TIA-1	usually positive1
granzyme B	usually positive
perforin	usually positive1
TCR	most usually ab-positive, 25% gd-positive, negative in rare NK variant1
ALK
EBV	negative in most cases1

CD4-/CD8- variants occur1.

Differential diagnosis

An inflammatory panniculitis
cytophagic histiocytic panniculitis
see cutaneous T-cell lymphoproliferative disorders

Prognosis

Most cases are naturally aggressive, but responsive to chemotherapy. A minority are indolent1. Haemophagocytic syndrome is associated with a poor prognosis2.

References

World Health Organization Classification of Tumours, Tumours of the haematopoietic and lymphoid tissues, IARC Press 2001.

1Liu, V. and McKee, P.H. Cutaneous T-cell lymphoproliferative disorders: approach for the surgical pathologist: recent advances and clarification of confused issues. Adv Anat Pathol 2002;9:79-100.

2Gonzalez, C.L., Medeiros, L.J., Braziel, R.M. and Jaffe, E.S. T-cell lymphoma involving subcutaneous tissue. A clinicopathologic entity commonly associated with hemophagocytic syndrome. Am J Surg Pathol 1991;15:17-27.

This page last revised 19.12.2002.