Pathology Outlines

Lung tumor

Mesenchymal

Hamartoma

Author: Roseann Wu, M.D., M.P.H.

Topic Completed: 1 August 2016

Minor changes: 15 December 2019

Copyright: 2002-2019, PathologyOutlines.com, Inc.

PubMed Search: Hamartoma [title] soft tissue

Page views in 2019: 13,112

Page views in 2020 to date: 7,048

Table of Contents

Cite this page: Wu R. Hamartoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/lungtumorhamartoma.html. Accessed August 7th, 2020.

Definition / general

Benign, generally solitary lesion composed of mature but disordered hyaline cartilage, fat and smooth muscle, with entrapped clefts of respiratory epithelium
Also called pulmonary chondroma, although chondromas in Carney triad are often multiple, occur more in women, have thin fibrous pseudocapsule, frequent ossification or calcification, and lack entrapped epithelium and fat (Am J Surg Pathol 2007;31:1844)
Nonfamilial Carney triad: pulmonary chondroma, gastric stromal tumors, functional extra-adrenal paraganglioma

Essential features

Most common benign tumor of lung, most often with chondromatous element
Typically solitary, < 4 cm, composed of disordered but mature hyaline cartilage, fibrous tissue, smooth muscle, fat, sometimes with calcification / ossification
Shows some overlapping features with pulmonary chondroma of Carney triad, but hamartomas tend to be single rather than multiple, favor men rather than women, and show entrapped respiratory epithelium and fat, without a fibrous pseudocapsule

Terminology

Pulmonary chondroma sometimes used interchangeably with pulmonary chondromatous hamartoma, but true pulmonary chondromas of Carney triad may be a distinct entity
Descriptive term sometimes added to describe components, i.e. lipomatous, chondroid, chondromatous, fibrochondromatous, fibroleiomyomatous
If lacks cartilage, could be diagnosed as lipoma, myxoma, leiomyoma or fibroadenoma

Epidemiology

Most common benign neoplasm of lung
Generally adults 40s to 60s, peripheral lesions more common in men

Sites

Mostly arise in peripheral lung; endobronchial in < 10% of cases

Etiology

Thought to arise from primitive mesenchymal tissue

Clinical features

Asymptomatic, slow growth
Occasionally with hemoptysis or may present with obstructive symptoms if endobronchial

Diagnosis

Usually incidental; radiologic diagnosis may be confirmed with FNA biopsy or excision

Radiology description

Incidental coin lesion; well circumscribed, small, smooth to lobulated nodule, with irregular nodular “popcorn” calcifications
Xray: non-specific soft tissue mass, sometimes with calcification
CT: May contain intralesional fat, calcifications

Radiology images

Images hosted on PathOut servers:

Contributed by Dr. Hanni Gulwani

Chest Xray

CT scan

Prognostic factors

Slowly enlarges if not excised
Rare exceptional cases of malignant evolution reported

Case reports

30 year old man with multiple pulmonary chondroid hamartomas (J Thorac Oncol 2014;9:1053)
35 year old man with giant pulmonary chondroid hamartoma (Clin Nucl Med 2015;40:79)
50 year old man with incidental pulmonary hamartoma diagnosed by FNA (BMJ Case Rep 2013 Mar 25;2013)
55 year old and 68 year old men with fibroleiomyomatous hamartoma (Pathol Int 2014;64:618, Surg Case Rep 2016;2:53)
77 year old man with pulmonary chondromatous hamartoma with pleural dissemination (Surg Today 2015;45:1197)
2 cases of salivary gland-type tumors showing myoepithelial differentiation arising in pulmonary hamartoma (Am J Surg Pathol 2006;30:375)

Treatment

Surveillance for biopsy proven asymptomatic pulmonary hamartomas, with resection for symptomatic patients or when diagnosis in doubt (Interact Cardiovasc Thorac Surg 2015;21:773)
Excision is curative

Clinical images

Images hosted on other servers:

Large endobronchial hamartoma

Gross description

Usually 4 cm or less, rarely > 10 cm
Sharply delineated and lobulated, unencapsulated
Glistening, translucent, homogenous, firm to hard cut surface (cartilaginous) with ill defined clefts and connective tissue septa
Tan-white to gray without cystic change or hemorrhage

Gross images

Images hosted on PathOut servers:

Contributed by Dr. Hanni Gulwani

Lobulated tumor

Images hosted on other servers:

Various images

Microscopic (histologic) description

Variable mixture of mature hyaline cartilage, fat or smooth muscle
Entrapped clefts lined by respiratory epithelium (ciliated or not)
Cartilage may be calcified or ossified
Periphery of cartilage may contain immature myxomatous tissue
Resembles breast fibroadenoma if no cartilage present
Entrapped small airways or alveolar epithelium with cuboidal metaplasia, hyperplasia, papillae
15% have papillary projections resembling immature placental villi (placental transmogrification), with stromal macrophages and lymphocytes and abundant mast cells (Arch Pathol Lab Med 2002;126:562)
Consider other diagnosis if see multinucleated cells, pleomorphism, mitoses, necrosis, which occur only rarely

Microscopic (histologic) images

Images hosted on PathOut servers:

Contributed by Dr. Hanni Gulwani