Multifocal micronodular pneumocyte hyperplasia associated with tuberous sclerosis

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Multifocal micronodular pneumocyte hyperplasia associated with tuberous sclerosis
Diagnosis in short

Micronodule of pneumocyte hyperplasia in multifocal micronodular pneumocyte hyperplasia associated with tuberous sclerosis. H&E stain.
LM DDx atypical adenomatous hyperplasia of the lung
IHC cytokeratin +ve, surfactant apoproteins (A & B) +ve, HMB-45 -ve
Molecular mutations in TSC1 or TSC2
Site lung

Associated Dx lymphangioleiomyomatosis - also assoc. with tuberous sclerosis
Syndromes tuberous sclerosis

Prevalence rare
Radiology ground-glass nodules, +/-emphysematous changes
Prognosis benign
Clin. DDx multifocal AAH

Multifocal micronodular pneumocyte hyperplasia associated with tuberous sclerosis, also multifocal micronodular pneumocyte hyperplasia in tuberous sclerosis, is the presence of a rare relatively distinctive hamartomatous lesion of the lung in multiple foci in a person with tuberous sclerosis.[1]

General

Clinical:

Gross

Features:[2]

  • Multiple small lung nodules.
    • Random distribution. ‡
    • Up to 5 mm in size.

Radiology:

  • May have an emphysema-like picture due to the obstruction of lymphatics and alveolar ducts from mass effect.[3]
  • Nodules have ground-glass appearance on CT.[2]

Notes:

  • ‡ One paper says peripheral location and upper lobe predominant.[1]

Microscopic

Features:

  • Macrophages within the air spaces.
  • Enlarged alveolar lining cells with:
    • Hobnail morphology - free (luminal) surface area > attached/basal surface area.
    • Round or oval nuclei.

DDx:

Images

IHC

Features:[2]

  • Cytokeratin +ve.
  • Surfactant apoprotein A +ve.
  • Surfactant apoprotein B +ve.

Others:[2]

  • HMB-45 -ve.
  • SMA (alpha) -ve.
  • p53 -ve.

See also

References

  1. 1.0 1.1 Nagar, AM.; Teh, HS.; Khoo, RN.; Morani, AC.; Vrishni, K.; Raghuram, J. (Feb 2008). "Multifocal pneumocyte hyperplasia in tuberous sclerosis.". Thorax 63 (2): 186. doi:10.1136/thx.2006.076604. PMID 18234663.
  2. 2.0 2.1 2.2 2.3 2.4 Kobashi, Y.; Sugiu, T.; Mouri, K.; Irei, T.; Nakata, M.; Oka, M. (Jun 2008). "Multifocal micronodular pneumocyte hyperplasia associated with tuberous sclerosis: differentiation from multiple atypical adenomatous hyperplasia.". Jpn J Clin Oncol 38 (6): 451-4. doi:10.1093/jjco/hyn042. PMID 18535095.
  3. 3.0 3.1 Popper, HH.; Juettner-Smolle, FM.; Pongratz, MG. (Apr 1991). "Micronodular hyperplasia of type II pneumocytes--a new lung lesion associated with tuberous sclerosis.". Histopathology 18 (4): 347-54. PMID 2071093.