Hematopathology

Authors

Michelle Don, MD (Resident) and Qin Huang, MD (Faculty)

Subject: Hematopathology
Clinical History

A 53-year-old female with longstanding mild anemia was found to have a solitary 0.5 cm papule on her right shoulder that had persisted for 2 months. No other suspicious cutaneous lesions were identified and the remainder of her clinical exam was unremarkable. After a month of treatment with topical creams, and no improvement in the lesion, a punch biopsy was performed.

Figures
biopsy, dense dermal nodular infiltrate, pathology, Cedars-Sinai

Figure 1: Punch biopsy showing a dense dermal nodular infiltrate extending into the subcutis.

pathology, pleomorphic atypical lymphoid, cell

Figure 2: Small to medium sized, pleomorphic, atypical lymphoid cells with admixed plasma cells.

pathology, cells, t-cell, marker, Cedars-Sinai

Figure 3: The Atypical lymphoid cells strongly express T-cell markers CD3 (A) and CD4 (B), and show evidence of follicular T-helper cell phenotype with expression of PD1 (C).

Comprehensive Immunohistochemistry Results
Strongly Positive in majority of atypical lymphoid cells:
Positive in minority of atypical lymphoid cells:
Positive in rare large lymphoma cells

CD3

CD20

CD30

CD4

CD8

CXCL13

PD1

CD7

BCL6

CD5

CD10

CD43

BCL2

Molecular Studies

T-cell receptor β-gene and γ-gene rearrangement positive.

Diagnosis

Overall, the findings are most consistent with involvement by a peripheral T-cell lymphoma with characteristic features of Primary Cutaneous Small/Medium CD4 Positive T-Cell Lymphoma (PC-SMTCL).

Discussion

PC-SMTCL is a type of primary cutaneous T-cell lymphoma characterized by a predominance of small to medium sized CD4-positive pleomorphic T-cells. There should be no evidence of any lesion typical of mycosis fungoides. Most cases present with a solitary skin lesion and the patient is otherwise asymptomatic. The biopsy often shows a dense dermal infiltrate of pleomorphic atypical T-cells that tend to infiltrate into the subcutaneous tissue. Epidermotropism should be mostly absent. The atypical cells express CD3 and CD4 and are without expression of CD8 and CD30. There is commonly a CD20 B-cell population and admixed plasma cells present. This entity was classified as a provisional entity in the 2008 WHO classification of lymphoid neoplasms and has since been further studied. The cells are now known to have a follicular T-cell phenotype with expression of PD1, ICOS, CXCL13, BCL-6, and CD10 at varying degrees. Although clonal rearrangements of TCR genes are seen, the 2016 revision of the WHO classification of lymphoid neoplasms refers to this entity as likely not meeting criteria for classification as a malignancy, but rather a clonal response to a stimulus that is not known. The terminology that should now be used is primary cutaneous CD4 positive small/medium T-cell lymphoproliferative disorder. The prognosis remains excellent.

References

1. Ally MS, Robson A. A review of the solitary cutaneous T-cell lymphomas. Journal of Cutaneous Pathology 2014;41:703–714.

2. Ha Lan TT, Brown NA, Hristov AC. Contraversies and considerations in the diagnosis of primary cutaneous CD4 small/medium T-cell lymphoma. Archives of Pathology and Laboratory Medicine. 2014;138:1307–1318.

3. Swerdlow, S.H., Campo, E., Pileri, S.A., Harris, N.L., Stein, H., Siebert, R., Advani R., Ghielmini, M., Salles, G.A., Zelenetz, A.D., Jaffe, E.S. The 2016 revision of the World Health Organization classification of lymphoid neoplasms. Blood; 2016(127)20: 2375-2390.

3. Swerdlow, S.H., Campo, E., Harris, N.L., Jaffe, E.S., Pileri, S.A., Stein, H., Thiele, J., Vardiman, J.W. WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues. IARC. 4th Ed. 2008

4. Williams VL, Torres-Cabala CA, Duvic M. Primary cutaneous small to medium sized CD4 pleomorphic T-cell lymphoma a retrospective case series and review of the provisional cutaneous lymphoma category. American Journal of clinical Dermatology 2011;12(6):389–401.

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