Dermatologie

Cas 0807670

Liens et agrandissements sur : images et texte en bleu. Links - Zoom: pictures and highlighted text.
 
Nodule violacé de la joue avec une bordure érythémateuse, chez un homme de 55 ans.
Violaceous nodule with an erythematous border of the cheek, 55 yo male.
 
 
Biopsie chirurgicale
Surgical biopsy
 
 
 
 
 
 
 
 
 
 
 
 
 
 
EMA
 
 
 
PAS (follicle and perifollicular area)
Reticuline
 
 
CD20
CD20
 
 
CD79a
CD79a
 
 
CD3
CD3
 
 
CD10
CD10
 
 
BCL2
BCL2
 
 
MIB1
MIB1

Diagnostic proposé

 

 

 

 

 

 

 

 

Lymphome cutané à cellules B de la zone marginale.

Proposed diagnosis

 

 

 

 

 

 

 

 

Cutaneous B-cell marginal zone lymphoma

 

Arguments

Dans le texte, en gras (bleu), de la réference ci-dessous:

 

 

In the highlighted (blue) text of the reference below:

 
 

Pathology and Genetics of Skin Tumours

World Health Organization Classification of Tumours

IARCPress Lyon, 2006

 

Cutaneous marginal zone B-cell lymphoma

Definition
Primary cutaneous marginal zone B-cell lymphoma (MZL) is an indolent lymphoma composed of small B cells including marginal zone (centrocyte-like) or monocytoid cells, lymphoplasmacytoid cells and plasma cells. It is considered part of the broad group of extranodal marginal zone B-cell lymphomas commonly involving mucosal sites (mucosa associated lymphoid tissue, MALT).
Primary cutaneous immunocytoma, primary cutaneous plasmacytoma and cutaneous follicular lymphoid hyperplasia with monotypic plasma cells are considered variants of MZL.


Synonyms
EORTC (1997): Primary cutaneous immunocytoma / marginal zone B-cell lymphoma


Epidemiology
MZL most commonly affects adults aged over 40 years. There is no clear gender preponderance.


Etiology
In Europe, Borrelia burgdorferi DNA has been identified in some cases of MZL suggesting that it may play an etiological role. However, no association of Borrelia with CBCL has been found in the United States and Asia.


Localization
MZL is predominantly localized on the upper extremitites, and less often head and trunk.


Clinical features
In most cases, cutaneous MZL presents with red to violaceous plaques or nodules with an erythematous border. Ulceration and visceral dissemination are uncommon. MZL with secondary spread to the skin is often multifocal.


Histopathology
The infiltrate is characterized by residual reactive (x40) lymphoid follicles (x100 - x200) surrounded by pale staining cuffs of tumour cells. Reactive germinal centres with distinct mantle zones are commonly found in early lesions but may become colonized by tumour cells as the disease progresses (x400). The interfollicular infiltrate is composed of small to medium-sized, centrocyte- like or monocytoid cells with slightly irregular nuclei, moderately dispersed chromatin, inconspicuous nucleoli and a rim of pale cytoplasm. Variable numbers of lymphoplasmacytoid cells and plasma cells are typically present at the periphery of the infiltrates or in the subepidermal area. Intranuclear PAS positive pseudoinclusions (Dutcher bodies), are commonly found, particularly in plasma cell rich forms of MZL. Diffuse infiltrates almost completely consisting of monocytoid cells, lymphoepithelial lesions (absence, EMA)with infiltration of sweat glands and the presence of very immature plasma cells should raise suspicion of secondary cutaneous involvement.


Immunoprofile
The neoplastic cells express CD19+, CD20+, CD22+, CD79a+, but are negative for CD5-, CD10-, bcl-6, CD23-. CD43 may be positive. In contrast to FL, the tumour cells are bcl-2+, but negative for bcl-6 and CD10. Reactive germinal centres are bcl-6+ and bcl-2-. Anti-CD21 staining often reveals regular and irregular networks of follicular dendritic cells (FDC) in reactive follicles, but not associated with tumour cells. The lymphoplasmacytoid cells and the plasma cells show monotypic expression of immunoglobulin light chains. There are numerous admixed reactive T-cells.


Precursor lesion
Cutaneous lymphoid hyperplasia due to Borrelia infection may mimic MZL and has been postulated to represent a precursor lesion in some circumstances.


Histogenesis
Post germinal centre B-lymphocyte with plasmacytic differentiation and gene expression pattern.


Somatic genetics
IgH genes are clonally rearranged. The most common translocation in gastric MZL, the t(11;18) involving the API2/MLT genes, has not been demonstrated in primary cutaneous MZL. However, the t(14;18)(q32;q21) involving IGH and MALT1 was reported in approximately one third of cases in a small series. Fas gene mutations are present in a minority of cases, similar to MZL of other extranodal sites. Abnormalities of BCL10 are absent.


Prognosis
MZL shows a protracted clinical course with a tendency for recurrences. However, the prognosis is favourable with 5-year-survival rates between 90 and 100%. Transformation into diffuse large B cell lymphoma occurs infrequently.

For more details on cutaneous lymphomas, see (click) the review article below

  Abstract from : BLOOD, 15 MAY 2005 VOLUME 105, NUMBER 10  
  Primary cutaneous marginal-zone B-cell lymphoma  

Histopathology.

These lymphomas show nodular (reticulin x40)to diffuse infiltrates with sparing of the epidermis (x100). The infiltrates are composed of small lymphocytes, marginal zone B cells (centrocyte-like cells), lymphoplasmacytoid cells, and plasma cells, admixed with small numbers of centroblast- or immunoblast-like cells and many reactive T cells. Reactive germinal centers are frequently observed. They may be surrounded by a population of small- to mediumsized
cells with irregular nuclei, inconspicuous nucleoli, and abundant pale cytoplasm (marginal zone B cells). Monotypic plasma cells are often located at the periphery of the infiltrates and in the superficial dermis beneath the epidermis periodic acid-schiff (PAS) intranuclear or intracytoplasmic inclusions may be present in cases with a predominance of lymphoplasmacytoid cells. PCMZLs rarely show transformation into a diffuse large B-cell lymphoma, but a relative increase in large transformed cells can be seen in some cases.


Immunophenotype.

The marginal zone B cells express CD20, CD79a, and bcl-2, but are negative for CD5, CD10, and bcl-6, which may be useful in distinction from PCFCL. Reactive germinal centers are typically bcl-6, CD10, and bcl-2. Plasma cells express CD138 and CD79a, but generally not CD20, and
show monotypic cytoplasmic immunoglobulin light chain expression on paraffin sections.