Use of an expanded immunohistochemical panel to distinguish cutaneous Hodgkin lymphoma from histopathologic imitators

Hodgkin Reed-Sternberg-Like Cells in Non-Hodgkin Lymphoma

Reed-Sternberg cells (RSCs) are hallmarks of classic Hodgkin lymphoma (cHL). However, cells with a similar morphology and immunophenotype, so-called Reed-Sternberg-like cells (RSLCs), are occasionally seen in both B cell and T cell non-Hodgkin Lymphomas (NHLs). In NHLs, RSLCs are usually present as scattered elements or in small clusters, and the typical background microenviroment of cHL is usually absent. Nevertheless, in NHLs, the phenotype of RSLCs is very similar to typical RSCs, staining positive for CD30 and EBV, and often for B cell lineage markers, and negative for CD45/LCA. Due to different therapeutic approaches and prognostication, it is mandatory to distinguish between cHL and NHLs. Herein, NHL types in which RSLCs can be detected along with clinicopathological correlation are described. Moreover, the main helpful clues in the differential diagnosis with cHL are summarized.

Specific infiltrate of Hodgkin lymphoma at site of cellulitis mimicking secondary cutaneous involvement

Hodgkin lymphoma (HL) usually involves the lymph nodes, but concomitant cutaneous manifestations can also occur. The diagnosis of cutaneous involvement by HL must be supported by specific clinical and histopathological findings. We describe the case of a 56-year-old man recently diagnosed with HL of the left axillary nodes who developed cellulitis of the left trunk. Histopathological examination of a skin biopsy specimen revealed the presence of large atypical lymphoid cells with the same immunophenotype of those located in the lymph node affected by HL. Our case adds to the many cutaneous infiltrations by neoplastic cells during the course of an inflammatory skin disease, namely cellulitis.

Cutaneous localization of angioimmunoblastic T-cell lymphoma may masquerade as B-cell lymphoma or classical Hodgkin lymphoma: A histologic diagnostic pitfall

BACKGROUND

We report the cases of three patients presenting skin lesions whose biopsies showed nodular polymorphic infiltrates consisting of lymphocytes, plasma cells, histiocytes, eosinophils, B blasts, and Hodgkin Reed-Sternberg (HRS)-like cells. Two of them were initially diagnosed as classical Hodgkin lymphoma (cHL), on the other hand, the last one as a B-cell lymphoma. All patients have been treated for angioimmunoblastic T-cell lymphoma (AITL).

METHODS

We performed a second review of the skin biopsies with further immunophenotypic molecular analyses. Scrupulous observation revealed, in the background of the three cases, atypical small to medium-sized lymphocytes carrying a CD3+, CD4+ T-cell phenotype and expressing PD1 and CXCL13 follicular helper T-cell markers. The two lesions initially diagnosed as cHL showed scattered HRS-like cells with CD30+, CD15+, PAX5+, CD20-, Epstein Barr Virus (EBV) + classical phenotype. The case initially diagnosed as B-cell lymphoma showed a diffuse B-cell proliferation associated with small B-cell and medium to large-sized B blasts that were positive for EBV.

CONCLUSION

Those cases highlighted that atypical T-cells may be obscured by B-cell proliferation mimicking cHL or B-cell lymphoma in cutaneous localization of AITL and confirmed the requirement of collecting clinical information before performing a diagnosis.

Use of ancillary techniques in improving the yield of samples obtained at endoscopic ultrasound-guided fine needle aspiration of thoracic and abdominal lymph nodes

OBJECTIVES

Thoracic and abdominal lymph nodes may be enlarged in a variety of disorders. Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is a well-established technique for sampling such nodes, but samples obtained are small, which may make definitive diagnosis difficult. We conducted a retrospective review to determine the contribution of ancillary techniques, such as special histochemistry (SHC), immunohistochemistry (IHC) and flow cytometry, in increasing the diagnostic yield of EUS-FNA carried out at our institution.

STUDY DESIGN

Between November 2005 and December 2012, 278 patients underwent EUS-FNA of enlarged thoracic and abdominal nodes at our institution. All specimens obtained were subjected to rapid on-site evaluation. Data were reviewed in all patients requiring ancillary techniques for definitive diagnosis.

RESULTS

Ancillary techniques were performed in 111 of 278 cases. IHC was performed in 24, flow cytometry in 3 and SHC staining in 84. IHC and SHC aided in reaching a definitive diagnosis in 19 of 24 and 3 cases, respectively. Flow cytometry led to a definitive diagnosis in 3 cases. A total of 80 cases were also submitted to culture for tuberculosis with 6 positive for Mycobacterium tuberculosis.

CONCLUSIONS

Ancillary studies in EUS-FNA of thoracic and abdominal lymph nodes can significantly improve the yield of EUS-FNA.

Immunohistochemistry in the era of personalised medicine

BACKGROUND

Immunohistochemistry (IHC) plays a central role in the histopathological classification of diseases, including cancer. More recently, the importance of immunohistochemical staining is increasing. IHC usage in diagnostics is invaluable; however, the genetic and therapeutic significance of biomarker immunostaining has become equally relevant.

CONTENT

In this article, we would like to analyse the three distinct roles of IHC and review their individual impacts on modern diagnostic pathology: (1) diagnostic IHC; (2) genetic IHC and (3) therapeutic IHC.

SUMMARY

Thus, we will characterise the different analytical processes that are required in the three approaches to IHC usage stated above, as well as the clinical significance and overall importance in patient management. This will allow us to hypothesise on the most appropriate laboratory environment and detection methods for the future.