Mycosis fungoides / Sezary's syndrome

Mycosis fungoides / Sézary's syndrome

Definition

Mycosis fungoides: A T-cell lymphoma of skin characterised by epidermal and dermal infiltration by small to medium size cells with cerebriform nuclei.

Sézary syndrome; a variant of mycosis fungoides with a leukaemic component and much more aggressive behavior.

Synonyms

Epidemiology

Mycosis fungoides accounts for only 0.5% of all non-Hodgkin lymphomas, but is the most common cutaneous T-cell lymphoma. Rarely, Mycosis fungoides occurs in children, where the histology and immunohistochemistry are as for adult disease1.

Sézary syndrome is a rare disease of adults.

Clinical features

 Mycosis fungoides: usually remains confined to the skin for years, with late dissemination to lymph nodes liver spleen, lungs and blood. The initial lesions are patches or plaques on the trunk, eventually progressing to tumours. Variants are discussed below.

Sézary syndrome: there is disseminated disease involving the skin, lymph nodes and blood. Patients present with erythroderma, pruritus, alopecia and lymphadenopathy.

Histopathology

Mycosis fungoides: there is an epidermotropic infiltrate of small to medium size cells with cerebriform nuclei. The formation of Pautrier abscesses is highly characteristic but is not always present. The dermal infiltrate may be patchy, band-like or diffuse. It is often accompanied by an infiltrate of small lymphocytes and eosinophils. Lymph node involvement may be staged:

Variants

Sézary syndrome: skin lesions are similar to those of Mycosis fungoides. Lymph node show a diffuse or paracortical infiltrate. The circulating cells may be small (Lutzner cells) or large (classical Sézary cells). There may be an elevated CD4/CD8 ratio. The bone marrow infiltrate is often sparse.

 

Immunohistochemistry

 

Mycosis fungoides

Sézary's syndrome

CD1a

   

CD2

positive

CD3

positive

CD4

positive

usually positive

CD5

positive

CD7

usually negative

variable

CD8

usually negative

rarely positive

CD11b

   

CD16

   

CD25

variable

 

CD30

often positive in pagetoid reticulosis

 

CD56

   

CD57

   

TCR

b-positive, rarely d-positive

b-positive

TdT

   

TIA-1

   

HECA

usually positive

 

ALK

   
     

†: fresh frozen tissue only

Differential diagnosis

Prognosis

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.

This page last revised 23.12.2002.

©SMUHT/PW Bishop