Case Number : Case 2916 - 09 September 2021 Posted By: Saleem Taibjee

This is a fascinating mixture of pathological changes. 

There is a predominantly perivascular, lymphocytic infiltrate with prominent eosinophils, and an area of flame figure formation in the upper dermis.  The dermal papillae show vacuolar change and oedema, with some small neutrophilic microabscesses.

I was caught out by a previous case of Saleem's (2781, 4th March) where the diagnosis was dermatitis herpetiformis with prominent eosinophils, so I wonder if this might be another similar case.  The anatomical distribution would do for it.  Of course bullous pemphigoid and a drug reaction would need to be considered (especially with the history of renal cancer), and scabies must be excluded.   Eosinophilic cellulitis is unlikely given the widespread anatomical involvement.

I would suggest deeper sections and immunofluorescence.

Found this: Rajpara A, Liolios A, Fraga G, Blackmon J. Recurrent paraneoplastic wells syndrome in a patient with metastatic renal cell cancer. Dermatol Online J. 2014 Jun 15;20(6):13030/qt35w8r1g3. PMID: 24945651.

...but agree with Richard: clinical feature doesn’t fit well EC. On low magnification flame figure sounds me like lined up with the vesicular epidermal lesion. So Scabies would be a good diff. 

This pattern has a number of differential as suggested by earlier comments. Those variably-sized merging little white spaces within oedematous papillary dermis in image 2, may well be incipient sub-epidermal separation/vesiculation rather than vaculoar interface changes.

BP worth exclusion with IMF +/-ELISA for BP180/230 though he is relatively young age but odd paraneoplastic antigen cross reactivity can occur.

Eosinophilic Dermatosis of Haematological Malignancy (EDHM) and Churg-Strauss are a couple of additional histological DDx that requires CPC. Not aware of EDHM (as the name suggests) in other neoplastic conditions and this used to be called insect-bite like reaction in CLL in earlier literature, but such nomenclature loses sensitivity and specificity with time as it is described in other diseases. 

Hi. I'm afraid I don't have a final answer for this case. I have not had any update from the clinician.

My own thoughts are... yes there is focal intraepidermal and subepidermal clefting, but the most striking changes are in the reticular dermis with a dense perivascular and interstitial infiltrate comprising lymphocytes, histiocytes, neutrophils and numerous eosinophils with flame figures. I also feel that there is eosinophilic degeneration of the collagen itself, with a hint of a palisaded arrangement. There is some deeper perivascular inflammation also.

To me eyes, the additional neutrophils and, in particular, eosinophilic collagen degeneration (contrast with basophilic degeneration in Wegeners) is quite suggestive of allergic granulomatosis with polyangiitis (formerly Churg-Strauss). I also considered drug reaction, arthropod reaction (e.g. scabies), Well's and hypereosinophilic syndrome. Unfortunately we don't have immunofluorescence to further assess for immunobullous disease (e.g. DH, pemphigoid), but I felt the dermal changes made this less likely anyway.

I will let you know if I do get any further update.

BW

Saleem