• 71F asymptomatic patient noted to have pulmonary nodules followed over 16 years via CT. A nodule in the right middle lobe (RML) increased in size from 4 mm to 9 mm and became PET avid, while other nodules remained stable and PET negative. Most likely diagnosis: DPNLH.
• Comment : The slow growth over time and selective PET avidity are key findings that help differentiate this condition from malignancy.
• Source: Ashley Davidoff, TheCommonVein.com, b12424-03c.1k.
A 71-year-old asymptomatic female with multiple pulmonary nodules followed over 16 years via CT imaging. Images show multiple nodules in a peripheral subpleural location. One of the nodules demonstrates a central lucency, likely reflecting a bronchocentric nature (red arrowhead). The distribution of nodules follows a linear perilymphatic pattern, either along the bronchovascular bundles or the venules (bcd), consistent with lymphatic distribution.(Image
Source: Ashley Davidoff, TheCommonVein.com, Case ID: b12424-06L)
A 71-year-old asymptomatic female with multiple pulmonary nodules followed over 16 years via CT imaging. The right middle lobe (RML) nodule, initially 4 mm, increased to 9 mm over 10 years. The CT scan (left image) shows the nodule, while the PET scan (right image) demonstrates FDG avidity, suggesting metabolic activity. The most likely diagnosis is Diffuse Pulmonary Nodular Lymphoid Hyperplasia (DPNLH).
(Image Source: Ashley Davidoff, TheCommonVein.com, Case ID: b12424-05)
| Category | Details |
|---|---|
| What is it? | A rare, benign lymphoproliferative disorder characterized by the presence of multiple pulmonary nodules composed of hyperplastic lymphoid tissue. |
| Etymology | “Nodular Lymphoid Hyperplasia” refers to the excessive proliferation of lymphoid tissue forming nodules in the lungs. |
| AKA | Nodular Lymphoid Hyperplasia (NLH), Pulmonary Nodular Lymphoid Hyperplasia (PNLH) |
| Characterized by | Multiple well-defined pulmonary nodules, reactive lymphoid proliferation, presence of reactive germinal centers, absence of systemic lymphoproliferative disorders. |
| Anatomically affecting | Pulmonary parenchyma, bronchovascular interstitium, typically subpleural and peribronchovascular distribution, associated with lymphatics of the venules. |
| Age and Sex | More common in middle-aged adults, slight female predominance. |
| Position in the Lungs | Predominantly involves the lower lobes, but may also be seen in middle and upper lobes, possibly due to larger lung volumes in the lower lung zones facilitating antigen exposure and immune surveillance. |
| Pathophysiology | Hyperplasia of B-cell lymphoid tissue with reactive germinal centers, lymphoid follicular hyperplasia without clonal proliferation, associated with immune dysregulation and chronic antigenic stimulation. |
| Most Common Causes | Immune (chronic antigenic stimulation, autoimmune disorders like Sjögren’s syndrome, rheumatoid arthritis), Inflammation (chronic inflammatory conditions), Neoplasm (benign lymphoproliferative disorder). |
| Other Causes | Infection (e.g., tuberculosis, fungal infections), Mechanical (chronic airway irritation), Metabolic (not typically associated), Circulatory (not a primary cause), Infiltrative (reactive infiltrative process), Inherited and Congenital (no known genetic predisposition), Iatrogenic (chronic immunosuppression), Idiopathic (no identifiable cause), Functional (not relevant), Psychiatric and Psychological (not relevant). |
| Histopathology | Well-defined nodules composed of benign lymphoid aggregates, reactive germinal centers with polyclonal B-cells, absent atypical or monoclonal B-cell populations (excluding lymphoma). |
| CT Imaging | Parts: Multiple pulmonary nodules, Size: Typically <3 cm, Shape: Well-defined, round to oval, Position: Predominantly in lower lobes, but may be seen in upper lobes, Character: Homogeneous, non-cavitating, may have air bronchograms, Time: Stable over long periods, slow-growing. |
| CXR Imaging | Non-specific round opacities, often missed unless multiple nodules are present. |
| MRI Imaging | Rarely used but may show T2 hyperintensity in lymphoid aggregates. |
| PET-CT Imaging | Mild to moderate FDG uptake, differentiating from malignancy. |
| Other Diagnostic Tests | Labs: Often normal, may show mild polyclonal hypergammaglobulinemia, PFTs: Usually normal unless extensive involvement affects lung function. |
| Differential Diagnosis | Pulmonary lymphoma, sarcoidosis, granulomatous infections (e.g., tuberculosis, fungal infections), lymphoid interstitial pneumonia, metastatic nodules, organizing pneumonia, immunoglobulin G4-related disease (IgG4-RD). |
| Recommendations | Clinical correlation with autoimmune conditions, histopathological confirmation via biopsy if malignancy is suspected. |
| Treatment | Observation: If asymptomatic and stable, Corticosteroids: If associated with inflammatory/autoimmune conditions, Surgical Resection: If nodules are growing or causing symptoms. |
| Prognosis | Excellent, usually benign with minimal progression, rare cases of transformation to lymphoma reported. |
| Radiological Implications | Recognition of benign features to avoid unnecessary biopsies or treatments, differentiation from neoplastic and infectious processes. |
| Key Points and Pearls | Rare benign lymphoid proliferation of the lungs, typically asymptomatic or mild respiratory symptoms, stable on imaging over time (differentiating from malignancy), more common in older populations, predominantly in lower lobes, often peripheral, subpleural, and bronchovascular, may be associated with pulmonary veins, linked to lymphatics of venules, and more frequent in lower lobes due to larger lung volumes and increased antigen exposure. |