Diagnostic Workup for Anaplastic Large Cell Lymphoma

Initial Clinical Assessment

• Document the presence and anatomic location of lymphadenopathy or extranodal masses (e.g., mediastinal, hepatosplenic, cutaneous, soft‑tissue) to guide staging and biopsy planning. – NCCN Guidelines 1
• In patients with breast implants, breast swelling, asymmetry, or peri‑implant fluid collection typically develops >1 year (median 8–10 years) after implantation, raising suspicion for implant‑associated ALCL. – ASCO Guidelines 2, 3

Tissue Acquisition Strategy

Systemic Disease

• Obtain an excisional or incisional biopsy rather than fine‑needle aspiration because ALCL may show focal involvement and requires adequate tissue for morphologic, immunophenotypic, cytogenetic, and molecular studies. – ASCO Guidelines 2, 4

Breast‑Implant‑Associated ALCL (BIA‑ALCL)

• When a peri‑implant effusion is present, perform ultrasound‑guided aspiration as the primary diagnostic procedure. – ASCO Guidelines 5, 2
• Process fresh effusion fluid immediately:
  
  • Cytocentrifugation to produce air‑dried smears stained with Wright‑Giemsa or Romanowsky‑type stains. – ASCO Guidelines 2, 4
  • Cell‑block preparation for H&E, immunohistochemistry, and PCR‑based T‑cell receptor (TCR) gene rearrangement studies. – ASCO Guidelines 2, 3
  • Flow cytometry (if a validated CD30 antibody is available) as a second‑line test after cytology and cell‑block. – ASCO Guidelines 6, 7

Pathologic Evaluation

Morphology

• Large pleomorphic cells with irregular nuclei, prominent nucleoli, and abundant basophilic cytoplasm are characteristic of ALCL. – ASCO Guidelines 5
• “Hallmark cells” with horseshoe‑ or kidney‑shaped nuclei are a distinctive but not universally present feature. – ASCO Guidelines 6

Immunohistochemistry (IHC)

• Mandatory markers:
  
  • CD30 – strong, uniform membranous expression is required for diagnosis. – ASCO & NCCN Guidelines 6, 7, 1
  • ALK (ALK‑1) – distinguishes ALK‑positive from ALK‑negative disease and carries prognostic significance. – NCCN Guidelines 1
  • Pan‑T‑cell markers (CD3, CD2, CD5, CD7) – often show aberrant or incomplete expression. – NCCN Guidelines 1
  • CD4 and CD8 – helpful for phenotypic classification. – NCCN Guidelines 1
• Additional markers to exclude mimics:
  
  • CD20, PAX5, CD138 – to rule out B‑cell lymphomas. – ASCO Guidelines 6, 7
  • Pan‑cytokeratin – to exclude poorly differentiated carcinoma. – ASCO Guidelines 6
  • EBV‑EBER in‑situ hybridization – to exclude EBV‑associated lymphomas. – ASCO Guidelines 6
  • Cytotoxic proteins (TIA‑1, granzyme B, perforin) – frequently positive in ALCL. – NCCN Guidelines 1

Flow Cytometry

• Typical immunophenotype: CD45⁺, CD30⁺, CD3⁻ or dim, often with aberrant T‑cell antigen expression. – ASCO & NCCN Guidelines 5, 1
• Pitfall: Reactive activated T cells may express CD30; correlation with morphology and light‑scatter properties is essential. – ASCO Guidelines 6, 7

Molecular & Cytogenetic Studies

• T‑cell receptor (TCR) gene rearrangement PCR (BIOMED‑2 primers) – detection of clonal rearrangements supports a neoplastic T‑cell process. – ASCO Guidelines 2, 6, 7
• Conventional cytogenetics (karyotype) on fresh tissue – provides chromosomal information useful for classification. – NCCN Guidelines 1
• For ALK‑negative ALCL:
  
  • FISH for DUSP22 rearrangement – associated with a favorable prognosis comparable to ALK‑positive disease. – NCCN Guidelines 1
  • FISH for TP63 rearrangement (when TP63 protein is positive by IHC) – identifies a high‑risk subgroup. – NCCN Guidelines 1

Staging Workup

• Imaging: Whole‑body PET/CT or contrast‑enhanced CT of the chest, abdomen, and pelvis. – NCCN Guidelines 1
• Bone‑marrow evaluation: Biopsy and aspirate with morphology, flow cytometry, and cytogenetics. – NCCN Guidelines 1
• Laboratory studies:
  
  • Complete blood count with differential. – NCCN Guidelines 1
  • Comprehensive metabolic panel, lactate dehydrogenase, uric acid, and phosphate to assess tumor burden and risk of tumor lysis. – ASCO Guidelines 8
  • HIV and HTLV‑1 serology in selected cases (HTLV‑1 positivity reclassifies disease as adult T‑cell leukemia/lymphoma). – NCCN Guidelines 1
  • Baseline cardiac assessment (echocardiogram or MUGA scan) when anthracycline‑based therapy is planned. – NCCN Guidelines 1

BIA‑ALCL Specific Staging & Management

• Capsular mapping at capsulectomy – systematic examination of the fibrous capsule to determine microscopic tumor involvement and depth of invasion (T‑stage 1–4). – ASCO Guidelines 7, 4
• Lymph‑node assessment: Excisional biopsy is preferred over fine‑needle aspiration because of the propensity for focal disease. – ASCO Guidelines 2, 3, 4

Diagnostic Pitfalls

• BIA‑ALCL may be missed if peri‑implant effusion fluid is not processed promptly or if the capsulectomy specimen is inadequately sampled, leading to false‑negative results. – ASCO Guidelines 2, 4