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SUMMARY
Cutaneous lymphomas are divided into T-cell and B-cell groups.
The most common primary cutaneous T-cell lymphomas (CTCLs) are mycosis fungoides (MF) and its leukemic counterpart, Sézary syndrome (SS).
MF pathogenesis evolves from resident memory T cells, which play a role in skin immune surveillance. SS pathogenesis evolves from central memory T cells, which contribute to circulating immune surveillance.
Classic MF clinical manifestations include patches, plaques, tumors, and generalized erythroderma. SS clinical manifestations include generalized erythroderma and lymphadenopathy.
Diagnosis is made with clinical and pathologic correlation via punch biopsies and, if indicated, flow cytometry of peripheral blood.
Histopathology for MF and SS is notable for intermediate-sized dysplastic cerebriform T cells with enlarged hyperchromatic nuclei.
When disease is limited to patches/plaques, therapy focuses on skin-directed treatments, whereas progression to tumors and erythroderma usually requires systemic therapy.
The most common primary cutaneous B-cell lymphomas (CBCLs) are (1) primary cutaneous follicle center lymphoma (PCFCL); (2) primary cutaneous marginal zone B-cell lymphoma (PCMZL); and (3) primary cutaneous diffuse large B-cell lymphoma, leg type (PCDLBCL-LT).
Clinical manifestations include the presence of purple to red nodules/papules on the head, neck, trunk, and legs. PCFCL and PCMZL have a more indolent disease course than PCDBCL-LT.
Diagnosis is made through punch biopsy with histopathology and immunophenotyping to differentiate subtypes.
Therapy includes radiotherapy, surgical excision, immunotherapy, and chemotherapy.
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DON’T FORGET
The diagnosis of CTCL or CBCL is a team effort between the clinician and pathologist.
Evolving and updated CTCL and CBCL treatment guidelines are published regularly by the National Comprehensive Cancer Network (NCCN).
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CLINICAL PEARLS
For patients presenting with signs and symptoms of persistent or poorly controlled atopic dermatitis, plaque psoriasis, tinea corporis, or erythroderma, consider MF and SS in your differential diagnosis.
For patients with new, isolated papules/nodules, consider CBCL in your differential.
For patients with underlying chronic lymphocytic leukemia (CLL) and small lymphocytic lymphoma (SLL), recognize the increased risk for nonmelanoma skin cancer.
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PATIENT EDUCATION POINTS
Cutaneous lymphomas are chronic diseases that require consistent monitoring to assess disease progression and response to therapy. Treatment is aimed at controlling, not curing, the disease and may consist of topical, oral, or intravenous medications with surgical intervention depending on severity.
Cutaneous leukemias are often signs of underlying malignancy that may require further exploration for diagnosis and treatment. Additional serial monitoring for increased risk of nonmelanoma skin cancers is necessary.
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PRIMARY CUTANEOUS LYMPHOMAS
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Cutaneous lymphomas are a heterogeneous group of non-Hodgkin lymphomas (NHLs) of T- and B-cell origin in which the skin is the primary organ of involvement. Primary cutaneous lymphomas usually present without signs of extracutaneous malignancy at the onset of symptoms; they represent an entity distinct from nodal lymphomas with secondary cutaneous involvement. This chapter will provide a comprehensive and clinically focused overview of primary cutaneous T-cell lymphomas (CTCLs) and primary cutaneous B-cell lymphomas (CBCLs), highlighting their ...