View source for Primary mediastinal B-cell lymphoma

'''Primary mediastinal B-cell lymphoma''', abbreviated '''PMBL''', is an uncommon form of large B-cell lymphoma.

It is also known as '''primary mediastinal large B-cell lymphoma'''.

==General==
Features:<ref name=pmid19074109 >{{Cite journal  | last1 = Johnson | first1 = PW. | last2 = Davies | first2 = AJ. | title = Primary mediastinal B-cell lymphoma. | journal = Hematology Am Soc Hematol Educ Program | volume =  | issue =  | pages = 349-58 | month =  | year = 2008 | doi = 10.1182/asheducation-2008.1.349 | PMID = 19074109 }}</ref><ref name=pmid20207294>{{Cite journal  | last1 = Coso | first1 = D. | last2 = Rey | first2 = J. | last3 = Bouabdallah | first3 = R. | title = [Primary mediastinal B-cell lymphoma] | journal = Rev Pneumol Clin | volume = 66 | issue = 1 | pages = 32-5 | month = Feb | year = 2010 | doi = 10.1016/j.pneumo.2009.12.007 | PMID = 20207294 }}</ref> 
*Rare.
*Young adults, more common in females (M:F = 1:2)
*[[Mediastinum]]
It is distinguished from DLBCL based on the patient demographics, radiological staging (showing mainly mediastinal disease) and immunoprofile (typically CD23+/CD30+). PMBCL has a better prognosis than DLBCL.

==Microscopic==
Features:
*Atypical large lymphoid cells - may be morphologically indistinguishable from ''[[DLBCL]]''
*Classically associated with:
**Fibrosis
**Clear cells.

Note:
*Neither fibrosis or clear cells are required for the [[diagnosis]] nor are they pathognomonic.<ref name=pmid11251018 >{{Cite journal  | last1 = van Besien | first1 = K. | last2 = Kelta | first2 = M. | last3 = Bahaguna | first3 = P. | title = Primary mediastinal B-cell lymphoma: a review of pathology and management. | journal = J Clin Oncol | volume = 19 | issue = 6 | pages = 1855-64 | month = Mar | year = 2001 | doi =  | PMID = 11251018 }}</ref>

DDx:
*Other types of [[DLBCL]] (radiological assessment is important - PMBCL is centred in the mediastinum)
*B-cell lymphoma with features intermediate between [[DLBCL]] and classical Hodgkins lymphoma
*Poorly differentiated carcinoma.

==IHC==
*Pan B-cell markers
*CD10 in minority (~20%)
*CD23 and CD30 expression more common (~70% and ~85% respectively)
*EBV negative

===Images===
<gallery>
Image:Primary_mediastinal_large_B-cell_lymphoma_-_very_high_mag.jpg | PMBL - very high mag. (WC)
Image:Primary_mediastinal_large_B-cell_lymphoma_-_intermed_mag.jpg | PMBL - intermed. mag. (WC)
</gallery>
www:
*[http://path.upmc.edu/cases/case371.html PMBL - several images (upmc.edu)].

==Sign out==
<pre>
MASS, ANTERIOR MEDIASTINAL, CORE BIOPSY:
- LARGE B-CELL LYMPHOMA IN A FIBROTIC BACKGROUND WITH NECROSIS, SEE COMMENT

COMMENT:
Morphology:
 Tumour cells: size ~2x a mature lymphocyte, a moderate quantity of grey/basophilic
  cytoplasm, no clear cells are identified.
 Cells intermixed with tumour: mature lymphocytes, rare eosinophils.
 Architecture: no gland formation, discohesive, no follicles apparent, extensive fibrosis.

Tumour cells:
POSITIVE: CD45, CD20, CD10, BCL-6, BCL-2.
NEGATIVE: pankeratin, PLAP, CD3, CD30.
Ki-67: 50% of large (lymphoid) cells.
</pre>

==See also==
*[[Lymphoma]].
*[[Diffuse large B-cell lymphoma]].

==References==
{{Reflist|2}}

[[Category:Diagnosis]]
[[Category:Lymphoma]]