Case Number : Case 638 - 19 Nov Posted By: Guest

Marginal zone lymphoma vs. diffuse FCC lymphoma

mcc vs lymhoma for ihc

Marginal zone lymphoma

Marked Grenz zone, diffuse and nodular pattern deep to the subQ.
Diffuse follicular centered lymphoma or diffuse large B cell lymphoma.
May need bcl-2, bcl-6, and CD-10 for differential.

Tumor MF , adnexotropic MF > diffuse FCC

Diffuse type of Follicle Centre Cell Lymphoma vs. diffuse large BCL

Diffuse large B-cell lymphoma

Unfortunately, the case was uploaded without the CD4 image and so most of you understandably went down the B-cell lineage. This case was kindly shared with me by Richard Carr. It is particularly interesting because it shows how (A) immunohistochemistry is critical when diagnosing lumphomas in the skin and ( rare tumors may sometimes present in or secondarily involve the skin. The CD56 was also positive. This is therefore an example of CD4+, CD56+ hematodermic lymphoma (blastic natural killer cell lymphoma) involving the skin. It commonly affects the skin and is thought to be derived from plasmacytoid dendritic cells. It would not be possible to make the diagnosis on H/E.

Alright wrong lineage. Tumor stage MF VS CD4+, CD56+ cutaneous lymphoma

I think that the clinical history is very much against tumor stage MF which arises against a background of prior patch and plaque stage disease. In this case the clinical history was of a single cutaneous nodule which would argue strongly against MF

Sorry my second comment were posted without refreshing the web page so I missed your diagnostic comment. Were other markers of NK cells negative?

I have now seen a couple of cases of this entity and one thing that strikes me
is that it is a completely monomorphic population of small to medium sized
mononuclear cells but (but lacks small reactive lymphocytes, plasma cells,
histiocytes that are typically found in the vast majority of lymphomas of all
types). If you just do CD3 and CD20 and forget the LCA you can be ruling out
a lot of different small round blue cells tumours before the penny finally drops!!

Once you do the CD4 and CD56 you can make a diagnosis with near confidence from
the end of the bench! Other CD3- / CD56 positive tumours exist like 1. Nasal
type NK/T-cell lymphoma (+ve for cytotoxic proteins and EBV). 2. ALCL can rarely
express CD56 and often CD4+ but also CD30+ and larger cells. 3. PCTCL NOS with
rare CD56 expression and variable markers.

The haematodermic neoplasm or plasmacytoid dendritic cell tumour has the following:
Positive
CD4, CD43, CD56, CD45, CD45RA, CD38
CD123, HLA-DR, BDCA-2, BDCA-4, TCL-1
Occasionally Positive
CD7, CD33, TDT, CD68, CD10, CD34, CD34, CD2
Negative
CD3 (surface), CD5, CD8, CD13, CD19, CD20, CD57, CD79a, CD117, Lambda, Kappa,
Myeloperoxidase, Lysozyme, NSE, Cytotoxic proteins, S100, EBV

In this patient the initial nodule was followed 4 weeks later by disseminated
cutaneous nodules. The patient responded favourably to initial chemotherapy
but this disease typically has a dismal prognosis despite all treatment options.

Thanks Dr. Carr for the detailed review. This is an amazing learning resource thanks to Dr. McKee and the contributors.