Pulmonary meningothelial-like nodule

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Pulmonary meningothelial-like nodule
Diagnosis in short

Pulmonary meningothelial-like nodule. H&E stain.

Synonyms pulmonary chemodectoma

LM small cell nests (expanding alveolar septa) with whorled appearance/streaming; composed of bland cells with round/ovoid nuclei without appreciable nucleoli
LM DDx lung tumourlet, poorly differentiated carcinoma, lobular breast carcinoma
IHC PR +ve, vimentin +ve, EMA +ve, CD56 +ve, chromogranin A -ve, synaptophysin -ve, S-100 -ve
Gross tan or yellow nodules - pleural or parenchymal, typically 1-3 mm
Site lung

Associated Dx poorly understood association with lung tumours - esp. lung adenocarcinoma
Clinical history typically an incidential finding
Prevalence very common
Prognosis benign
Treatment none

Pulmonary meningothelial-like nodule, abbreviated MLN, is a common benign finding in the lung.

They are also referred to as minute pulmonary meningothelial-like nodules (abbreviated MPMN) and minute pulmonary chemodectoma.[1]

General

  • Benign.[2]
  • Very common - seen in almost half of well sampled lobectomies.[3]
  • May be grouped with pulmonary meningioma in the larger category primary pleuropulmonary meningothelial proliferations.[4]
  • Can mimic metastatic deposits.[2][5]

Associations:

  • More common in females (odds ratio 2).[6]
  • Seen more frequently in the context of cancer - esp. adenocarcinoma.[6]

Gross

  • Tan or yellow nodules - pleural or parenchymal - typically 1-3 mm.[1]

Note:

  • Found in all lobes.[6]
  • May be seen on imaging if large.[2]

Microscopic

Features:[1]

  • Small cell nests - expanding alveolar septa.
    • Whorled appearance/streaming.
    • Composed of bland cells with round/ovoid nuclei without appreciable nucleoli.

DDx:

Images

Case 1

Case 2

www

IHC

Features:

  • CD56 +ve (18 of 18 cases[3]).
  • EMA +ve (11 of 11 cases[3]).
  • Vimentin +ve (10 of 14 cases[1]).
  • PR (18 of 18 cases[3]).

Others:[1]

  • S-100 -ve.
  • NSE -ve.
  • Cytokeratin -ve.
  • Actin -ve.

Images

See also

References

  1. 1.0 1.1 1.2 1.3 1.4 Gaffey, MJ.; Mills, SE.; Askin, FB. (Mar 1988). "Minute pulmonary meningothelial-like nodules. A clinicopathologic study of so-called minute pulmonary chemodectoma.". Am J Surg Pathol 12 (3): 167-75. PMID 2830799.
  2. 2.0 2.1 2.2 Lee, SK.; Kim, GJ.; Kim, YJ.; Leem, AY.; Hwang, ED.; Kim, SK.; Chang, J.; Kang, YA. et al. (Aug 2013). "Minute pulmonary meningothelial-like nodules simulating hematogenous lung metastasis: a case report.". Tuberc Respir Dis (Seoul) 75 (2): 67-70. doi:10.4046/trd.2013.75.2.67. PMID 24023559.
  3. 3.0 3.1 3.2 3.3 Mukhopadhyay, S.; El-Zammar, OA.; Katzenstein, AL. (Apr 2009). "Pulmonary meningothelial-like nodules: new insights into a common but poorly understood entity.". Am J Surg Pathol 33 (4): 487-95. doi:10.1097/PAS.0b013e31818b1de7. PMID 19047895.
  4. Weissferdt, A.; Tang, X.; Suster, S.; Wistuba, II.; Moran, CA. (Aug 2015). "Pleuropulmonary Meningothelial Proliferations: Evidence for a Common Histogenesis.". Am J Surg Pathol. doi:10.1097/PAS.0000000000000489. PMID 26291511.
  5. 5.0 5.1 5.2 Kfoury, H.; Arafah, MA.; Arafah, MM.; Alnassar, S.; Hajjar, W. (Feb 2012). "Mimicry of Minute Pulmonary Meningothelial-like Nodules to Metastatic Deposits in a Patient with Infiltrating Lobular Carcinoma: A Case Report and Review of the Literature.". Korean J Pathol 46 (1): 87-91. doi:10.4132/KoreanJPathol.2012.46.1.87. PMID 23109985.
  6. 6.0 6.1 6.2 Mizutani, E.; Tsuta, K.; Maeshima, AM.; Asamura, H.; Matsuno, Y. (May 2009). "Minute pulmonary meningothelial-like nodules: clinicopathologic analysis of 121 patients.". Hum Pathol 40 (5): 678-82. doi:10.1016/j.humpath.2008.08.018. PMID 19144385.