Lymph node pathology

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This article deals with non-haematologic malignant, i.e. metastases, and non-malignant lymph node pathology. An introduction to the lymph node is in the lymph nodes article.

Haematologic malignancies (in lymph nodes) are dealt with in other articles - see haematopathology and lymphoma.

Overview

Clinical:

  • Lymphadenopathy.

Differential diagnosis:[1]

  • Infectious - fungal, mycobacterial, viral, protozoal (Toxoplasma), bacterial (Chlamydia, Rickettsia, Bartonella)).
  • Neoplastic - lymphoma, carcinoma.
  • Endocrine - hyperthyroidism.
  • Trauma.
  • Autoimmune - SLE, RA, dermatomyositis.
  • Inflammatory - drugs (phenytoin).
  • Idiopathic - sarcoidosis.

Overview in a table

Entity Key feature Other findings IHC DDx Image
Non-specific reactive follicular hyperplasia (NSRFH) large spaced cortical follicles tingible body macrophages, normal dark/light GC pattern BCL2 -ve infection (Toxoplasmosis, HIV/AIDS), Hodgkin's lymphoma image ?
Lymph node metastasis foreign cell population, usu. in subcapsular sinuses +/-nuclear atypia, +/-malignant architecture dependent on tumour type (see IHC) dependent on morphology, endometriosis (mimics adenocarcinoma), ectopic decidua (mimics SCC)
 
CRC metastasis
 
Breast metastasis
Progressive transformation of germinal centers large (atypical) germinal centers poorly demarcated germinal center (GC)/mantle zone interfaces, expanded mantle zone IHC to r/o nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) NLPHL, follicular hyperplasia
 
PTGC - very low mag.
Toxoplasmosis large follicles; epithelioid cells perifollicular & intrafollicular reactive GCs, monocytoid cell clusters, epithelioid cells IHC for toxoplasma NSRFH, HIV/AIDS, Hodgkin's lymphoma
 
TL - low mag.
Kikuchi disease (histiocystic necrotizing lymphadenitis) No PMNs histiocytes, necrosis IHC for large cell lymphoma (CD30 + others) SLE (has (blue) hematoxylin bodies in necrotic areas), large cell lymphomas
 
HNL - very high mag.
Cat-scratch disease PMNs in necrotic area "stellate" (or serpentine) shaped microabscesses, granulomas B. henselae, Dieterle stain HIV/AIDS, NSRFH
 
Cat scratch - very low mag.
Dermatopathic lymphadenopathy melanin-laden histiocytes histiocytosis S100+ve (interdigitating dendritic cells), CD1a+ve (Langerhans cells) cutaneous T-cell lymphoma
 
DL - intermed. mag.
Kimura disease eosinophils angiolymphoid proliferation (thick-walled blood vessels with hobnail endothelial cells) IHC ? Langerhans cell histiocytosis, drug reaction, angiolymphoid hyperplasia with eosinophilia
 
Kimura disease - very high mag.
Langerhans cell histiocytosis abundant histiocytes with reniform nuclei often prominent eosinophilia S100+, CD1a+ Kimura disease (eosinophilia), Rosai-Dorfman disease
 
LCH - very high mag.
Rosai-Dorfman disease sinus histiocytosis emperipolesis (intact cell within a macrophage) S100+, CD1a- Langerhans cell histiocytosis
 
RDD - very high mag.
Systemic lupus erythematosus lymphadenopathy (blue) hematoxylin bodies necrosis, no PMNs IHC for large cell lymphoma (CD30 + others) Kikuchi disease, large cell lymphomas
 
SLEL - high mag.
Castleman disease, hyaline vascular variant thick mantle cell layer with laminar appearance ("onion skin" layering) hyaline (pink crap), lollipops (large vessels into GC), no mitoses in GC IHC - to r/o mantle cell lymphoma mantle cell lymphoma, HIV/AIDS
 
CD - intermed. mag.
Castleman disease, plasma cell variant thick mantle cell layer sinus perserved, interfollicular plasma cells, mitoses in GC HHV-8 HIV/AIDS image ?
Intranodal palisaded myofibroblastoma spindle cells with nuclear palisading RBC extravasation, fibrillary bodies with a central vessel "amianthoid fibers" SMA+, cyclin D1+ schwannoma
 
IPM - very high mag.

Follicular lymphoma vs. reactive follicular hyperplasia

Factors to consider:[2]

Reactive follicular
hyperplasia
Follicular lymphoma
Follicle location cortex cortex and medulla
Germinal center edge sharp/well-demarcated poorly demarcated
Germinal center density well spaced, sinuses open crowded, sinuses effaced/
compressed to nothingness
Tingible body
macrophages
common uncommon
Germinal center
light/dark pattern
normal abnormal

Lymph node metastasis

General

  • Determination of lymph node status is one of the most common indications for the examination of lymph nodes.
  • It is a good idea to look at the tumour (if available) ...before looking at the LNs for mets.
  • Lymph node metastasis, in the absence of other metastases, often up-stage a cancer from stage II to stage III.

Gross

  • Outside:
    • "Large" - size varies by site.
      • Neck >10 mm.[3]
    • Shape - round more suspicious than oval.
  • Sectioned:
    • White firm lesion with irregular border - classic appearance.
    • Non-fatty hilum.[3]

Microscopic

Features:

  • Foreign cell population - key feature.
    • Classic location: subcapsular sinuses.
  • +/-Cells with cytologic features of malignancy.
    • Nuclear pleomorphism (variation in size, shape and staining).
    • Nuclear atypia:
      • Nuclear enlargement.
      • Irregular nuclear membrane.
      • Irregular chromatin pattern, esp. asymmetry.
      • Large or irregular nucleolus.
    • Abundant mitotic figures.
  • +/-Cells in architectural arrangements seen in malignancy; highly variable - dependent on tumour type and differentiation.
    • +/-Gland formation.
    • +/-Single cells.
    • +/-Small clusters of cells.

Notes:

  1. Cytologic features of malignancy may not be present; some tumours, e.g. gallbladder carcinoma, do not always have overt cytologic features of malignancy.
    • The diagnosis is based on the fact that they are foreign to the lymph node and architecturally consistent with a well-differentiated malignancy.
  2. Lymph node metastases in sarcomas are uncommon; they are seen in <3% of cases.[4]
  3. Fatty lymph nodes (esp. fatty hilus[3]) are less likely to harbor metastases.[5]

DDx - mimics of metastatic disease:

Images

Mimics

Kaposi sarcoma

  • One of the few non-lymphoid primary lymph node tumours.[9]

Melanocytic nevi

See: Dermatopathic lymphadenopathy.
  • Benign melanocytic nevi can be found in lymph nodes.[9]

Progressive transformation of germinal centers

  • Abbreviated as PTGC.

Reactive follicular hyperplasia

General

  • Many causes - including: bacteria, viruses, chemicals, drugs, allergens.
    • In only approximately 10% can definitive cause be identified.[10]

Microscopic

Features:[11]

  • Enlarged follicles, follicle size variation - key feature with:
    • Large germinal centers (pale on H&E).
      • Mitoses common.
      • Variable lymphocyte morphology.
      • Tingible-body macrophage (large, pale cells with junk in the cytoplasm).
      • Germinal centers (GCs) have a crisp/sharp edge.
      • Normal dark/light variation of GCs; superficial aspect light, deeper aspect darker.
    • Rim of small (inactive) lymphocytes.

DDx:

Image: Normal lymph node (umdnj.edu).

IHC

Screening panel:

  • CD3.
  • CD5.
  • CD10.
  • CD20.
  • CD30.
  • CD15.

Others:

  • BCL2 -ve.

Diffuse paracortical hyperplasia

General

  • Benign.

Microscopic

Features:[11]

  • Interfollicular areas enlarged - key feature.
    • T cell population increased.
    • Plasma cells.
    • Macrophages.
    • Large Reed-Sternberg-like cells.

Sinus histiocytosis

General

  • Benign.
  • Non-specific finding.

Microscopic

Features:[11]

  • Sinuses distended with histiocytes - key feature.
  • Plasma cells increased.

DDx:

Sign out

  • The finding is often ignored; may be signed out as morphologically benign lymph nodes.

Kikuchi disease

  • AKA histiocytic necrotising lymphadenitis (HNL).[12]
  • AKA Kikuchi-Fujimoto disease.

General

  • Rare disease that may mimic cancer, esp. lymphoma.
    • May cause fever & systemic symptoms.[13]

Epidemiology:[13]

  • Usually <40 years old.
  • Asian.
  • Female:Male = 3:1.[14]

Treatment:

  • Usually self-limited.[13]
  • Oral corticosteroids.

DDx:

Micrograph

Features (the three main features - just as the name suggests):[15]

  • Histiocytes.
    • May be crescentic.
  • Necrosis (due to apoptosis) - paracortical areas.[13]
    • Necrosis without neutrophils - key feature.
  • Lymphocytes (CD8 +ve).
  • Plasmacytoid dendritic cells.

Notes:

  • Dendritic cell - vaguely resembles a macrophage:[16]
    • Long membrane projections - key feature.
    • Abundant blue-grey cytoplasm, +/- ground-glass appearance.
    • Nucleus: small, ovoid, usu. single nucleolus.

Images

www:

IHC

  • CD68 +ve.
  • CD8 +ve - usu. predominant.
  • CD4, CD20, CD3, and CD30 - mixed.
    • Done to excluded lymphoma; esp. large cell lymphomas;[17] should show a mixed population of lymphocytes.
  • Others:
    • CD56 -ve.

Systemic lupus erythematosus lymphadenopathy

General

Microscopic

Features:[18]

  • Necrosis.
  • Hematoxylin bodies (in necrotic foci).
    • Dark blue irregular bodies on H&E.

DDx:

Images

Castleman disease

  • AKA angiofollicular lymph node hyperplasia, giant lymph node hyperplasia.[19]
  • Abbreviated CD.

General

  • Benign.
  • Hyaline vascular variant - a pathology of the follicular dendritic cells.[20]

Classification

CD is grouped by histologic appearance:[21]

  1. Hyaline vascular (HV) variant (described by Castleman).
  2. Plasma cell (PC) variant.
    • Usually multicentric, may be unicentric.
    • Abundant plasma cells.
    • Associated with HHV-8 infection (the same virus implicated in Kaposi's sarcoma).

Notes:

  • The subclassification of CD is in some flux. Some authors advocate splitting-out HHV-8 and multicentric as separate subtypes.[23]

Microscopic

Hyaline-vascular variant

Features:[24][25]

  • Pale concentric (expanded) mantle zone lymphocytes - key feature.
    • "Regressed follicles" - germinal center (pale area) is small.
  • "Lollipops":
    • Germinal centers fed by prominent (radially penetrating sclerotic) vessels; lollipop-like appearance.
  • Two germinal centers in one follicle.
  • Hyaline material (pink acellular stuff on H&E) in germinal center.
  • Sinuses effaced (lost).
  • Mitoses absent.

Images

www:

Plasma cell variant

Features:[25]

  • Interfollicular sheets of plasma cells - key feature.
  • Active germinal centers - mitoses present.
  • Sinus perserved.

IHC

Hyaline-vascular variant:

Plasma cell variant:

  • HHV-8 +ve.

Cat-scratch disease

  • AKA Cat-scratch fever.

General

  • Infection caused Bartonella henselae,[26] a gram-negative bacilla (0.3-1.0 x 0.6-3.0 micrometers) in chains, clumps, or singular.[27]
  • Treatment: antibiotics.

Clinical

Features:[28]

  • Usually unilateral.
    • May be disseminated in individuals with immune dysfunction.
  • Contact with cats.

Micrograph

Features:[28]

  • Necrotizing granulomas with:
    • Neutrophils present in microabscess (necrotic debris) - key feature.
      • Microabscesses often described as "stellate" (star-shaped).
  • +/-Multinucleated giant cells.

Notes:

  • May involve capsule or perinodal tissue.

DDx of stellate abscess in lymph nodes - cat split:[29]

Images

www:

Stains

  • Warthin-Starry stain +ve.

IHC

  • B. henselae IHC stain +ve - diagnostic.

Toxoplasma lymphadenitis

General

  • Caused by protozoan Toxoplasma gondii.

Microscopic

Features:[28]

  • Reactive germinal centers (pale areas - larger than usual).
    • Often poorly demarcated - due to loose epithelioid cell clusters at germinal center edge - key feature.
  • Epithelioid cells - perifollicular & intrafollicular.
    • Loose aggregates of histiocytes (do not form round granulomas):
      • Abundant pale cytoplasm.
      • Nucleoli.
  • Monocytoid cells (monocyte-like cells) - in cortex & paracortex.
    • Large cells in islands/sheets key feature with:
      • Abundant pale cytoplasm - important.
      • Well-defined cell border - important.
      • Singular nucleus.
    • Cell clusters usually have interspersed neutrophils.

Images:

Notes:

  • Monocytoid cells CD68 -ve.

IHC

  • IHC for toxoplasmosis.

Dermatopathic lymphadenopathy

General

  • Lymphadenopathy associated with a skin lesion - key feature.
  • May be benign or malignant (e.g. T-cell lymphoma).

Microscopic

Features:[30]

  • Abundant histiocytes & special histiocytes - in loose irregular clusters - located in the sinuses, i.e. sinus histiocytosis - key feature:
    • Do not form granuloma; may be similar to toxoplasma.
  • Plasma cells (medulla).
  • Eosinophils.

Histiocytes & special histiocytes:

  • Histiocytes:
    • +/-Melanin pigment key feature (if present).
    • Lipid-laden macrophages.
  • Interdigitating dendritic cells:
    • Need IHC to identify definitively.
  • Langerhans cells:
    • Classically have a kidney bean nuclei.
    • Need IHC to identify definitively.

DDx:

Images

IHC

  • Interdigitating dendritic cells: S100 +ve, CD1a -ve.
  • Langerhans cells: S100 +ve, CD1a +ve.

Kimura lymphadenopathy

Microscopic

Features:

  • Abundant eosinophils.
  • Thick-wall blood vessels.

Rosai-Dorfman disease

  • Abbreviated RDD.

General

  • AKA sinus histiocytosis with massive lymphadenopathy, abbreviated SHML.[31]
  • Super rare.
  • Prognosis - good.

Microscopic

Features:

  • Sinus histiocytosis:
    • Histiocytes - abundant.
      • Singular large round nuclei[32] ~2x the size of resting lymphocyte.
        • Prominent nucleolus - visible with 10x objective.
      • Abundant cytoplasm.
  • Emperipolesis (from Greek: em = inside, peri = around, polemai = wander about[33]):
    • Histiocytes contain other whole cells: neutrophils, lymphocytes, plasma cells.
      • The "eaten" cell is within a vacuole;[34] thus, it should have a clear halo around it.
      • Thought to be related to peripolesis; the attachment of a cell to another.[35]

DDx:

Images

www:

IHC

  • CD68 +ve.
  • S100 +ve.
    • Useful for seeing emperipolesis.
  • CD1a -ve.
    • CD1a positive in Langerhans cell histiocytosis.

Langerhans cell histiocytosis

Microscopic

Features:

  • Langerhans cells histiocytes - key feature.
    • Clusters of cells (histiocytes) with a reniform (kidney-shaped) nucleus and abundant foamy cytoplasm.
  • +/-Eosinophils - often prominent.

See Langerhans cell histiocytosis for details.

Lymph node hyalinization

  • AKA hyalinized lymph node.

General

  • Benign.
  • Associated with aging.[36]

Microscopic

Features:

  • Hyaline material (acellular pink stuff on H&E) within a lymph node.

Subdivided into:[36]

  • Mediastinal-type.
    • Usually in medullary sinus.
    • Onion peel-like appearance.
  • Pelvic-type hyalinization.
    • Discrete round, eosinophilic, glassy appearance at low power, whirled/fibrous at high power.
    • +/-Calcification.

DDx:

  • Amyloidosis - cotton candy-like appearance, usu. no calcifications.

Images:

See also

References

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