[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [General pathology](https://durgical.com/en/general-pathology/) › [Lung](https://durgical.com/en/general-pathology/areas/lung/) › Other lung tumours and lung metastases

# Other lung tumours and lung metastases

- Lesion

Not every lung nodule is carcinoma: hamartomas are benign coin lesions, and the lung is the most common site of metastases from other cancers.

Updated Nov 12, 2026

## Key points

- Pulmonary hamartoma: well-circumscribed coin lesion of cartilage, fat and fibrous tissue with epithelial clefts; popcorn calcification; actually a clonal neoplasm (6p21 or 12q14-15 rearrangements, HMGA2).
- Inflammatory myofibroblastic tumour: children; spindle myofibroblasts with lymphocytes and plasma cells; ALK rearrangement in some (responds to ALK inhibitors).
- Lymphangioleiomyomatosis: young women; perivascular epithelioid cells with TSC2 loss (mTOR activation); cystic lungs, pneumothorax, chylous effusions.
- Lymphomas: extranodal marginal zone (MALT) lymphoma, lymphomatoid granulomatosis (EBV-positive B cells), Hodgkin lymphoma.
- Metastases: multiple discrete 'cannonball' nodules at the periphery; also lymphangitic spread, endobronchial and pleural forms.

## What it is

Besides carcinomas and neuroendocrine tumours, the lung hosts benign and malignant mesenchymal and lymphoid tumours. Pulmonary hamartoma is the classic benign coin lesion; inflammatory myofibroblastic tumour affects children; lymphangioleiomyomatosis affects young women. The lung is the commonest site of metastatic cancer, usually as multiple peripheral nodules.

## Structure

- Hamartoma: lobules of mature hyaline cartilage separated by clefts lined by respiratory epithelium, with fat and fibrous tissue.
- Inflammatory myofibroblastic tumour: firm grey-white mass of fascicles of spindle cells mixed with plasma cells and lymphocytes.
- Metastases: multiple rounded nodules that reproduce the histology of the primary; lymphangitic carcinomatosis fills lymphatics around bronchi and septa.
- Occasional lepidic growth by metastatic carcinoma can mimic adenocarcinoma in situ.

## Step by step

- Metastatic cells reach the lung through the blood (the lung filters venous return from the whole body), lymphatics or direct invasion.
- Cells lodge in the capillary bed and grow into peripheral nodules.
- Carcinomas of breast, stomach, pancreas and colon may spread along lymphatics (lymphangitic pattern).
- Oesophageal carcinoma and mediastinal lymphoma can invade the lung directly.

## Benign or uncommon lung tumours

| Tumour | Who | Key features |
| --- | --- | --- |
| [Pulmonary hamartoma](https://durgical.com/en/conditions/solitary-pulmonary-nodule/) | Adults, incidental | Cartilage, fat, epithelial clefts; popcorn calcification |
| Inflammatory myofibroblastic tumour | Children | Spindle myofibroblasts with plasma cells; ALK |
| [Lymphangioleiomyomatosis](https://durgical.com/en/conditions/tuberous-sclerosis-complex/) | Young women | Cysts, TSC2 loss, mTOR |
| [MALT lymphoma](https://durgical.com/en/conditions/non-hodgkin-lymphoma/) | Adults, autoimmune disease | Small B cells along bronchi (lymphoepithelial lesions) |

## Clinical notes

- A solitary nodule with popcorn calcification and fat on CT is typical of hamartoma.
- Multiple nodules in a patient with a known cancer suggest metastases (common primaries: breast, colon, kidney, sarcomas, melanoma, germ cell tumours).
- Lymphangitic spread causes progressive dyspnoea out of proportion to imaging.

## Memory aid

Hamartoma is a coin with popcorn; metastases are cannonballs.

## Test yourself

Think of the answer, then tap the question to see it.

## What is a pulmonary hamartoma made of?

Nodules of mature cartilage, fat and fibrous tissue with clefts lined by respiratory epithelium; it is a clonal benign neoplasm.

## Which site is the most common location of metastatic tumours?

The lung.

## What is lymphangioleiomyomatosis?

A proliferation of perivascular epithelioid cells with TSC2 loss in young women, causing cystic lungs, pneumothorax and chylous effusions.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/general-pathology/other-lung-tumours-and-lung-metastases/)

[More Pathology questions →](https://durgical.com/en/practice/?f=pathology)

## Connections

## Related 6

- [Pathways of spread and the usual metastatic sites](https://durgical.com/en/general-pathology/pathways-of-spread-and-the-usual-metastatic-sites/)
- [Benign vs malignant tumours: the comparison table](https://durgical.com/en/general-pathology/benign-vs-malignant-tumours-the-comparison-table/)
- [Lung carcinoma: histologic types](https://durgical.com/en/general-pathology/lung-carcinoma-histologic-types/)
- [Pulmonary neuroendocrine tumours](https://durgical.com/en/general-pathology/pulmonary-neuroendocrine-tumours/)
- [Metastases to the liver: the most common liver malignancy](https://durgical.com/en/general-pathology/metastases-to-the-liver-the-most-common-liver-malignancy/)
- [Gastrointestinal lymphoma](https://durgical.com/en/general-pathology/gastrointestinal-lymphoma/)

## Related conditions 3

- [Solitary pulmonary nodule](https://durgical.com/en/conditions/solitary-pulmonary-nodule/)
- [Lung cancer](https://durgical.com/en/conditions/lung-cancer/)
- [Non-Hodgkin lymphoma](https://durgical.com/en/conditions/non-hodgkin-lymphoma/)

[← All of general pathology](https://durgical.com/en/general-pathology/)

Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [Lung Cancer](https://medlineplus.gov/lungcancer.html) (MedlinePlus, US National Library of Medicine, 2025).

## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake

Representative model, for educational purposes only.

---
Source: https://durgical.com/en/general-pathology/other-lung-tumours-and-lung-metastases/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/general-pathology/other-lung-tumours-and-lung-metastases/