Lung

Mesenchymal tumors

Pulmonary hamartoma



Last staff update: 10 May 2022

Copyright: 2002-2022, PathologyOutlines.com, Inc.

PubMed Search: Pulmonary hamartoma[TI] free full text[SB]

Hui-Hua Li, M.D., Ph.D.
Jefree J. Schulte, M.D.
Page views in 2021: 12,575
Page views in 2022 to date: 7,010
Cite this page: Li HH, Schulte JJ. Pulmonary hamartoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/lungtumorhamartoma.html. Accessed July 5th, 2022.
Definition / general
  • Benign neoplasm composed of varying amounts of mesenchymal elements (cartilage, fat, connective tissue, smooth muscle) with entrapped respiratory epithelium
  • At least 2 mesenchymal elements should be present for diagnosis
Essential features
  • Most common benign pulmonary neoplasm, often incidentally found
  • Benign neoplasm composed of varying amounts of at least 2 mesenchymal elements combined with entrapped respiratory epithelium
  • Radiographic features often very characteristic
Terminology
  • Other names previously used in the literature (chondroid hamartoma, mesenchymoma, chondromatous hamartoma, hamartochondroma) are no longer recommended
ICD coding
  • ICD-O: 8992/0 - pulmonary hamartoma
  • ICD-11: 2F00.Y & XH3UD9 - other specified benign neoplasm of middle ear or respiratory system & pulmonary hamartoma
Epidemiology
Sites
Pathophysiology
Etiology
  • Thought to arise from mesenchymal tissue
  • Chromosomal aberrations may be a primary event in pulmonary hamartoma but unclear what other genetic events may be necessary to induce tumor development (Cancer Genet Cytogenet 2002;138:160)
Clinical features
Diagnosis
Radiology description
  • Small coin lesion, often solitary, characterized by smooth edge, focal fat or fat alternating with calcific foci (Ann Thorac Med 2015;10:231)
  • Calcifications often described as popcorn calcification
  • Intralesional fat and popcorn-like calcifications allow a confident diagnosis on CT (J Thorac Imaging 2016;31:11)
Radiology images

Contributed by Jeffrey P. Kanne, M.D.
Hamartoma with calcifications

With calcifications

Hamartoma CT scan

CT scan

Prognostic factors
Case reports
Treatment
Clinical images

Images hosted on other servers:

Bronchoscopy

Large endobronchial hamartoma

Large endobronchial mass

Gross description
  • Pale, firm, round to multilobulated, well circumscribed nodule (most are < 4 cm in diameter)
  • Endobronchial hamartoma manifests as yellow to gray sessile polyps of large airways
  • References: Mayo Clin Proc 1996;71:14, Thorax 1987;42:790
Gross images

Contributed by @Andrew_Fltv on Twitter
Pulmonary hamartoma Pulmonary hamartoma Pulmonary hamartoma

Pulmonary hamartoma



Images hosted on other servers:

Pneumonectomy specimen

Various images

Firm and discrete lesions

Various images

Resected endobronchial tumor

Microscopic (histologic) description
  • Composed predominantly of varying degrees of mesenchymal tissue: hyaline cartilage, fat, smooth muscle and bone
  • Other connective tissue elements may be present, represented by bland spindle cells, fibrous tissue or myxoid change
  • Variably conspicuous, entrapped benign epithelial cells
  • Reference: Thorax 1987;42:790
Microscopic (histologic) images

Contributed by Hui-Hua Li, M.D., Ph.D. and Jefree J. Schulte, M.D.
Hamartoma with cartilage

With cartilage

Fat rich hamartoma

Fat rich

Hamartoma, typical features

Typical features

Hamartoma, fat / myxoid stroma

Fat / myxoid stroma


Hamartoma, bland spindle cells

Bland spindle cells

Pulmonary hamartoma core biopsy

Core biopsy

Pulmonary hamartoma biopsy, cartilage

Biopsy, cartilage

Pulmonary hamartoma biopsy, epithelium

Biopsy, epithelium



Contributed by @Andrew_Fltv on Twitter
Pulmonary hamartoma Pulmonary hamartoma

Pulmonary hamartoma

Cytology description
  • FNA is highly reliable means of diagnosis (Cytopathology 2008;19:185)
  • Misclassification as malignancy can occur, especially at the time of immediate adequacy assessment, prior to review of all cytologic preparations (Cytopathology 2008;19:185, BMC Pulm Med 2003;3:2)
  • FNA often shows fibromyxoid tissue, fat or cartilage associated with benign reactive epithelial cells
  • Lack of cytologic atypia and bland chromatin should point towards a benign diagnosis (Acta Cytol 2009;53:201)
Cytology images

Images hosted on other servers:

FNA smears

Positive stains
  • Immunohistochemical markers are not typically needed to confirm diagnosis
  • Immunohistochemical profile should be typical for the mesenchymal tissue being stained
  • Interestingly, sex steroid receptors (ER, PR, AR) are often expressed (Am J Surg Pathol 2006;30:819)
Molecular / cytogenetics description
  • Often not needed for diagnostic purposes
  • High frequency of translocation t(3;12)(q27-28;q14-15) resulting in gene fusion of the HMGA2 and LPP genes (see Pathophysiology and Etiology above)
Sample pathology report
  • Lung, left, needle core biopsy:
    • Pulmonary hamartoma (see comment)
    • Comment: The histologic sections reveal the presence of a benign pulmonary lesion composed of hyaline cartilage, fibroadipose tissue, bone and bland spindle cells in myxoid stroma. The mesenchymal elements appear to entrap benign respiratory epithelium. These findings support the above diagnosis.
  • Lung, right, wedge resection:
    • Pulmonary hamartoma (3.2 cm) (see comment)
    • Comment: The histologic sections reveal the presence of a well circumscribed benign pulmonary lesion composed of hyaline cartilage, fibroadipose tissue, smooth muscle and bland spindle cells set in fibromyxoid stroma. The mesenchymal elements appear to entrap benign respiratory epithelium. These findings support the above diagnosis.
Differential diagnosis
  • Pulmonary chondroma:
    • Lacks entrapped epithelium
    • Does not contain secondary mesenchymal elements
    • Often seen in patients with Carney triad
  • Other soft tissue tumors (including leiomyoma and lipoma):
    • Only 1 mesenchymal component may be sampled at the biopsy
    • Radiographic (popcorn calcifications and fat) findings may help suggest the diagnosis of hamartoma
  • Primary / metastatic sarcoma:
    • Cytologic atypia and features of necrosis should be present for diagnosis of sarcoma
Board review style question #1

A 67 year old man died in a work related accident. At autopsy, a 1 cm, circumscribed nodule is identified in the peripheral lung. The cut surface reveals a tan-white rubbery nodule. The histologic findings are seen in the image above. The incidentally discovered tumor is best classified as

  1. Non small cell carcinoma
  2. Pulmonary chondroma
  3. Pulmonary hamartoma
  4. Pulmonary sequestration
Board review style answer #1
C. Pulmonary hamartoma

Comment Here

Reference: Pulmonary hamartoma
Board review style answer #2
A 60 year old man presents to the emergency department following a motor vehicle accident. A chest CT scan reveals a circumscribed solitary pulmonary nodule containing fibroadipose tissue and calcifications. The patient meets with a thoracic surgeon, who does not immediately recommend excision. The patient is followed by serial CT scans and the nodule shows minimal growth over the next year. The characteristics of this pulmonary nodule are those of

  1. High grade neuroendocrine carcinoma of the lung
  2. Metastatic carcinoma to the lung
  3. Non small cell lung carcinoma
  4. Pulmonary hamartoma
Board review style answer #2
D. Pulmonary hamartoma

Comment Here

Reference: Pulmonary hamartoma
Back to top
Image 01 Image 02