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Inflammatory pseudo tumour

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Clinical features

  • In the lung it is the most common isolated primary lesion in patients under 16 years of age
  • 56% of the  benign lung tumours in children
  •  Previous history of pulmonary disease
  • Usually asymptomatic
  • Mainly located in the apical segments of the lower lobes

Fig 91 – Inflammatory pseudotumor – Smear from a transthoracic guided fine needle aspiration – Poorly cohesive polymorphic population (fibroblasts, Histiocytes, lymphocytes and plasma cells) (H&E)

  • Polymorphic cellular population of:
    • Histiocytes
    • Fibroblasts
    • Lymphocytes
    • Plasma cells


  • Confirmation of the myofibroblastic origin of spindle cells:
    • Vimentin : Positive
    • Desmin: Positive
    • Muscle-specific actin: Positive

Modern Techniques of Diagnosis

Non contributory

Differential Diagnosis

  • Inflammatory lesions
  • Carcinoid (spindle cell pattern)
    • Monotonous population of neoplastic cells
    • Neuroendocrine “salt and pepper” chromatin
    • Absence of inflammatory cells

Main points

  • Excision is curative when complete. If not, progression to infiltration of local tissues can be a problem