July 1994, Volume 44, Issue 7

Original Article

Ki-1 Large Cell Anaplastic Lymphoma - A Clinicopathological Study

Sajid Mushtaq  ( Armed Forces Institute of Pathology, Rawalpindi. )
Iftikhar A. Malik  ( Armed Forces Institute of Pathology, Rawalpindi. )
Manzoor Ahmed  ( Armed Forces Institute of Pathology, Rawalpindi. )
M. Safdar Khan  ( Armed Forces Institute of Pathology, Rawalpindi. )
Amir Hussain Khan  ( Armed Forces Institute of Pathology, Rawalpindi. )
Shahid Jamal  ( Armed Forces Institute of Pathology, Rawalpindi. )
Fayyaz A. Malik  ( Armed Forces Institute of Pathology, Rawalpindi. )

Abstract

Ki-1 large cell anaplastic lymphoma is a recently described variant of malignant lymphoma. A retrospec­tive study of 1.0 cases of Ki-I lymphoma was carried out at the Armed Forces Institute of Pathology (AFIP) Rawalpindi to document its clinical and morphological features. The morphological features were evaluated by a study of paraffin embedded sections stained with haematoxylin and eosin stains. Immu­nohistochemical stains for BER-H2 and leucocyte common antigen (LCA) were performed in all cases. The age of the patients ranged from 2 to 60 years and male to female ratio was 2.3:1. Cervical lymphade­nopathy was the most common presentation. Histologically, there was a complete effacement of the lymph node architecture in 8 cases. The Reed-Sternberg like cells were seen in 2 and histiocyte like cells in 7 cases. Immunohistochemically all cases were positive for BER-H2. It is suggested that the possibility of Ki-1 lymphoma should be considered in all cases of lymphoma with pleomorphic morphology. (JPMA 44:169,1994).

Introduction

Ki-1 large cell anaplastic Jymphoma was initially described by Stein and colleagues1 by finding CD 30/Ki-1 antigen. It is composed of pleomorphic neoplastic cells and may be confused with metastatic carcinoma or malignant histiocytosis2. Immunohisto chemistry is essential to confirm the diagnosis. There is no documented report of this type of lymphoma in Pakistan. We report ten cases of Ki-1 lym­phoma, diagnosed at the Armed Forces Institute of Pathology (AFJP) Rawalpindi.

Patients and Methods

Ten cases of anaplastic large cell lymphoma were identified in the surgical pathology department of AFIP Rawalpindi during three years period (1990-1992). The biopsy material was fixed in 10% buffered formalin and was processed for paraffin embedding. The routine haematoxylin and eosin stain was done in all and Periodic-acid Schiff (PAS) and reticulin stains in some cases where required. Immunohistochemical stains were done on paraffin embedded tissues. The sections of 5 micrometer thickness were used for staining of BER-H2 (a monoclonal antibody equivalent to Ki-1) and leucocyte common antigen (LCA) in all cases. The stains for epithetial membrane antigen (EMA) were done in only two cases due to short supply of antibodies. Monoclonal antibodies were obtained from Biogenix Labora­tories.

Results

The clinical features of 10 cases are summarized in Table I.

There were 7 males and 3 females - Majority of cases were in the second and third decade of life. Lymphadenopathy was the presenting feature in 9, with cervical lymph nodes involvement in majority of the cases (5 out of 9). In one patient a skin rash was the initial presentation followed by cervical lymph adenopathy. These lymph nodes, regressed without any treatment but reappeared within two weeks along with back ache due to vertebral metastases. One case presented with abdominal mass and another with paraplegia. In at two year old child generalized lymphadenopathy with hepa­tosplenomegaly was seen. An initial histological diagnosis of metastatic carci­noma in lymph nodes was made in 8 cases, whereas one case was diagnosed as Hodgkin’s disease and another as malignant histiocytosis. The morphological features on mutine staining are given in Table II.

There was complete effacement of the lymph node architecture in 8 cases while 2 showed partial effacement. Two cases showed Reed- Stemberg type cells while histiocyte like cells were detected in 7 cases. A distinctive feature was the striking cellular pleomorphism (Figure 1)

ranging from bizarre multinucleated cells to cells with rounded nuclei. The mitotic rate ranged from one to 10 per high power fields. Immunohistochemical stains (Table III)

of lymph nodes showed positive staining for BER-H2 in all ten cases (Figure 2).

A strong LCA positivity was observed in 2 cases whereas 6 cases showed weak focal positivity with 2 being negative for LCA. The epithelial membrane antigen (EMA) staining was done in 2 cases and both revealed weak positivity.

Discussion

Ki-1 large cell lymphoma is a recently described variant of malignant lymphoma This is characterized by the presence of an antigen called Ki-l (CD3O) antigen1. Stein et al.3, reported that Ki-l antibody (CD3O) marked specifically the neoplastic cells of Hodgkin’s disease. Some other workers described unusualana plastic large cell lymphoma in which neoplastic cells express the Hodgkin’s related antigen Ki-11. It is a rate disease that constitutes about 2-7% of the non-Hodgkin’s lymphoma4. There is no conclusive data available regarding the geographical/epidemiological distribution of this disease probably because of its recent recognition as a separate entity. The disease is characterized by a bimodal age distribution with peaks in 3rd and 8th decades4,5. Majority of our cases were in second and third decade of life. This type of lymphoma is more common in males and this was true incases Clinical presentation is variable and commonly affected sites are lymph nodes, skin, bone and gastrointestinal tract4. The bulk of our cases presented with lymphadenopathy and only I case presented with skin rash. The regression of skin lesions and lymphadenopathy is another unusual feature of this lymphoma6, and such was observed. It is because of its pleomorphic appearance on histology, skin distribution and frequent reactivity with EMA that this lymphoma is often misdiagnosed as metastatic carcinoma in lymph nodes, or as malignant histiocytosis; regressing atypical histiocytosis, nodular sclerosing Hodgkin’s disease, sinusoidal large cell lymphoma and lymphomatoid papulosis2,4. Majority (80%) of our cases were initially diagnosed as metastatic carcinoma­tous deposits in lymph nodes. One case was diagnosed as malignant histiocytosis and another as Hodgkin’s disease. Immunohistochemistry helps greatly in the differential diagnosis of this disease. The Ki-l lymphomas are always positive for BER- H2 and majority are LCA positive but some may be negative, however, EMA is mostly positive. The tumour cells in Ki-l lymphoma normally stain positively for T-cell markets with some cases having B-cell type markers while others may not show any T- or B-cell differentiation (0-phenotype)4,7. All our cases were BER-H2 positive with negative LCA in 2 cases. We could do EMA staining in only 2 cases and both were weakly positive. It can be concluded that a diagnosis of Ki-l large cell lymphoma should be considered in any histologically pleo­morphic lymphoma as Ki-l lymphoma can simulate many other disorders. The diagnosis must be confirmed by immuno­histochemical studies.

References

1. Stein, H., Mason, D.Y., Gerdes, JO. et al. The expression of the Hodgkin’s disease associated antigen Ki-1 in reactive and neoplassic lymphoid tissue: evidence that Reed-Sternberg cells and histiocytic malignancies are derived from activated lym¬phoid cells. Blood, 1985;66:848-58.
2. Bsnks, P.M., Metter, J. and Allred, D.C. Anaplastic large cell (Ki-1) lymphosna with lsistiocytic phenotype simulating carcinoma. Am.J.Clin.Pathol., 1 990;94:445-52.
3. Stein, H., Gerdes, J., Schwab, U. et al. Identification of Hodgkin and Sternberg-Reed cells as a unique cell type derived from a newly-detected small cell population. Int.J.Cancer, 1982;30:445-59.
4. Agnarason, BA. and Kadin, ME. Ki-l positive large cell lymphoma, a morphologic and immunologic study of 19 cases. Am.J.Surg. Psthol., 1988; 12:264-74.
5. Kinneyh, M.C., Greec, J.P., Click, A.D. et al. Anaplassic large cell Ki-1 malignant lyrnphoma. Recognition biological and clinical implications. Pathol. Annu., 1991;26: 1-24.
6. Ohshima, K., Kiksschim, M., Mssuda, Y. et al. Genosypic and immunologic analytis of anaplastic large cell lymphoma (ki- 1). Pathol.Res.Pract., 1990; 1869:582-88.

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