|Year : 2015 | Volume
| Issue : 3 | Page : 150-152
Plasmablastic lymphoma developing in thyroid: a rare entity in an immunocompetent individual
Faiq Ahmed MD 1, Manasi C Mundada1, Sudha S Murthy1, Senthil J Rajappa2
1 Department of Laboratory Medicine, Basavatarakam Indo American Cancer Hospital and Research Institute, Hyderabad, Telangana, Andhra Pradesh, India
2 Department of Medical Oncology, Basavatarakam Indo American Cancer Hospital and Research Institute, Hyderabad, Telangana, Andhra Pradesh, India
|Date of Submission||05-May-2015|
|Date of Acceptance||15-May-2015|
|Date of Web Publication||8-Sep-2015|
Department of Laboratory Medicine, Basavatarakam Indo American Cancer Hospital and Research Institute, Road No. 10, Banjara Hills, Hyderabad - 500 034, Telangana, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
A case of plasmablastic lymphoma that has not been described previously in the thyroid is presented with its clinicopathological features and the diagnostic difficulties encountered. A detailed histopathology in conjunction with immunohistochemistry is recommended for appropriate diagnosis and management in the setting of HIV-negative status. Dealing with a case presenting primarily as a thyroid mass can be challenging in the scenario of a CD20-negative immunoprofile.
Keywords: immunocompetent, non-Hodgkin′s lymphoma, plasmablastic lymphoma, thyroid
|How to cite this article:|
Ahmed F, Mundada MC, Murthy SS, Rajappa SJ. Plasmablastic lymphoma developing in thyroid: a rare entity in an immunocompetent individual. Egypt J Haematol 2015;40:150-2
|How to cite this URL:|
Ahmed F, Mundada MC, Murthy SS, Rajappa SJ. Plasmablastic lymphoma developing in thyroid: a rare entity in an immunocompetent individual. Egypt J Haematol [serial online] 2015 [cited 2020 Feb 20];40:150-2. Available from: http://www.ehj.eg.net/text.asp?2015/40/3/150/164743
| Introduction|| |
Plasmablastic lymphoma (PBL) is a rare non-Hodgkin's lymphoma in which the proliferating B-cells has switched its phenotype to the plasma cell gene expression profile. Evidences on cases of PBL in the thyroid are lacking. Although in the HIV setting the preferred site of PBL is the oral cavity, in the non-HIV setting, various extraoral sites have been described  . This is the first case of PBL involving the thyroid, as an unusual presentation with diagnostic features and difficulties encountered in arriving at a diagnosis of such a rare entity, that will be discussed.
| Case history|| |
A 61-year-old man presented to our surgical outpatient department with a swelling in the midline neck of 3 months' duration. He also had a history of dysphagia and change in voice of 1-month duration. His medical history was not significant and there was a lack of any obvious immunosuppression. Physical examination indicated a large hard mass ~10 × 10 cm involving the thyroid with tiny small level IV cervical lymph nodes. MRI of the neck indicated a large lobulated isointense mass on T1W and a hyperintense mass on T2W images, measuring 11 × 8.2 × 7.4 cm, involving left lobe of the thyroid and the isthmus. This mass was causing a compression effect, with a mild shift of the trachea to the right side ([Figure 1]). The larynx was normal. Multiple small cervical lymph nodes were identified at the level IV region and the largest lymph node measured 1.8 cm. Fine-needle aspiration cytology performed from the thyroid raised the suspicion of lymphoma. Enzyme-linked immunosorbent assay for HIV was negative. A trucut biopsy under guidance was performed. The biopsy showed a diffuse lesion of large cells with a syncytial pattern and entrapped thyroid follicles. These cells were large, with round, central to peripherally placed nuclei, with single prominent nucleoli and few cells with coarse chromatin and smaller one to two nucleoli. Apoptosis and focal necrosis were noted ([Figure 2]a and b).
|Figure 1 MRI showing involvement of plasmablastic lymphoma in the left lobe and isthmus of the thyroid.|
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|Figure 2 (a) Entrapped thyroid follicles amidst the lesion (×40). (b) Cells with immunoblastic and plasmablastic morphology (×40).|
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In view of the morphologic diagnosis of a high-grade lymphoma, an initial panel of markers comprising of CD20, CD3, CD5, CD10, BCL6, and Ki67 was requested for. All the immunohistochemistry were negative and the tumor showed a high Ki67 proliferative index (90%). The negativity of specific B and T cell markers ([Figure 3]) raised a possibility of poorly differentiated carcinoma and anaplastic large cell lymphoma in our differentials. A secondary panel comprising of B lineage markers CD79a, Pax5, along with markers of anaplastic large cell lymphoma (CD30, ALK1), epithelial markers such as PCK, the thyroid transcription factor 1 marker for medullary carcinoma (calcitonin), along with leukocyte common antigen (LCA) was ordered. Except for faint reactivity to LCA, the neoplastic cells were negative for the entire battery of markers. Additional markers with CD138 showed strong positivity, along with MUM1 showing diffuse strong nuclear positivity, and CD56 was found to be negative ([Figure 4]a and b). Epstein-Barr virus (EBV) performed by rapid in-situ hybridization was negative. Staging and work-up with marrow evaluation indicated uninvolved marrow. Serum protein electrophoresis was normal, without any paraproteinemia. Serum albumin levels were normal (4.3 g/ml). On the basis of the clinical, morphological, and immunoprofile, the diagnosis of PBL was made.
|Figure 4 (a) CD138 strongly positive in neoplastic cells (×40). (b) MUM1 strong and diffuse positivity in neoplastic cells (×40).|
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| Discussion|| |
PBL is a rare and distinct B-cell neoplasm where the large cells have downregulated the B-cell differentiation program and express plasma cell markers. PBL accounts for 2.6% of non-Hodgkin's lymphoma in HIV-related neoplasm  , but is also increasingly being reported in immunocompetent individuals at unusual sites such as the lungs, stomach, cervical lymph nodes, nasal cavity, jejunum, anorectal junction, and larynx , . Previous studies have described 80 cases of HIV-negative PBL, with 75% subset of cases occurring in an immunocompetent host  . The median age reported was 57 years, and with advancing age, there is a decrease in immune-surveillance, which could be a contributing pathogenetic mechanism for the plausible cause of this disease  .
PBL can present a significant diagnostic challenge on morphologic and immunohistochemical grounds. The important criterion in the diagnosis of these lymphoma is strong positivity of CD138, CD38, VSCD38, and MUM1 and weak/absent expression of CD20 and CD79a  . Our case showed weak LCA reactivity with strong CD138 and MUM1 expression. In the thyroid, the morphology and CD20-negative immunoprofile can be mistaken for poorly differentiated carcinoma, which is more frequent than the unusual PBL. In contrast, the other differential diagnosis that has considerable overlap both morphologically and phenotypically is extramedullary plasmablastic myeloma. Differentiating this from PBL is very important as the management of both these entities varies. Distinction requires evaluation of clinical findings such as serum elecrophoresis, Bence-Jones proteins, and bone lytic lesions, which are more common in extramedullary plasmablastic myeloma than PBL. Immunohistochemistry with CD56 is found to be specific in plasma cell neoplasm compared with PBL as reported by a study of Colomo et al.  who described CD56 positivity in one of 18 cases of PBL. Our patient also lacked expression of CD56.
PBL are usually associated with latent EBV, encountered in 60-75% of cases  . EBV infection can be detected by fluorescence in-situ hybridization for EBV-RNA or PCR. However, immunohistochemistry for LMP1 has been described to be less sensitive in detecting latent EBV infection  . EBV testing performed in this case by rapid in-situ hybridization was negative. Castillo and Reagan  have described EBV positivity in 82 and 46% of the HIV-positive and HIV-negative cases, respectively, by the in-situ hybridization technique. HIV-negative patients with PBL are known to have worse prognosis than their HIV-positive counterparts  . There are no definitive uniform guidelines for the treatment of such cases and the treatment regime varies on the basis of the clinician's discretion. Our patient was started on cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP regimen); he showed a dramatic response and the patient is on follow-up.
| Conclusion|| |
To our knowledge, this is the first case of PBL being reported in the thyroid that warrants awareness in a CD20-negative setting.
| Acknowledgements|| |
The authors would like to thank Mr Sambasiva Reddy for his technical support.
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]