# The growth pattern on a basal cell carcinoma report: nodular, superficial, infiltrative, basosquamous

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## TL;DR

Basal cell carcinomas are sorted by the shape they grow in, and the shape decides how much skin has to be taken and who does it. Nodular and superficial patterns are low risk; infiltrating, sclerosing or morphoeic, and micronodular patterns are high risk because their edges are ragged and invisible. Most tumours contain more than one pattern, and the worst one present decides.

## Summary

WHO names the subtypes and Britain sorts them. The fourth edition of the WHO skin classification (2018) listed ten: nodular, superficial, micronodular, infiltrating, sclerosing or morphoeic, basosquamous carcinoma, pigmented, with sarcomatoid differentiation, with adnexal differentiation, and fibroepithelial (of Pinkus). The fifth edition (2025) lists the same nine minus pigmented basal cell carcinoma, which no longer has a heading of its own and survives as a related term under the general ICD-O code. The UK reporting dataset uses the WHO classification and divides growth pattern into low and high biological risk (RCPath G123).

The low-risk patterns. **Superficial** basal cell carcinoma is made of multiple small collections of follicular germ cells in contact with the epidermis or hair follicles, most widely defined as not extending beyond the papillary dermis, and all published thickness definitions are under 1 mm; it is often called multicentric or multifocal, which the dataset calls a misnomer since the apparently separate islands are usually continuous. It is often accompanied by a stromal reaction in the upper dermis that may be the only abnormality visible in a small biopsy. The dataset notes that there is no consensus on whether superficial basal cell carcinoma is in situ or invasive, which is why its title avoids the phrase invasive basal cell carcinoma altogether. **Nodular** basal cell carcinoma grows as nodules of varying size, sometimes cystic or with keratin cysts, larger than the micronodules below; it is the commonest pattern. **Fibroepithelial** basal cell carcinoma (of Pinkus) is contested, with a long argument over whether it is a basal cell carcinoma or a benign trichoblastoma; WHO and therefore the UK dataset treat it as low risk.

The high-risk patterns. **Infiltrating** basal cell carcinoma grows as irregular islands and strands with a jagged or spiky outline. **Sclerosing or morphoeic** is that same infiltrating pattern with dense stromal fibrosis around it, which is what makes a morphoeic tumour feel like a scar and makes its edge impossible to see. **Micronodular** grows as small round nodules of follicular bulb size, defined as under 0.15 mm across, roughly fewer than 25 cells wide; the dataset asks that the term be kept for tumours that also infiltrate at the edge. All three are reported together in the UK as **infiltrative basal cell carcinoma**, because, in the dataset's words, there is no clinical value in distinguishing them for management or treatment, and they often co-exist in one tumour with overlapping forms. Naming them individually is optional.

**Basosquamous** carcinoma is not a growth pattern but a differentiation: a basal cell carcinoma containing a moderately or severely atypical or frankly malignant squamous component. The term has been used loosely for collision tumours and for the poorly defined metatypical basal cell carcinoma, but there is reasonable evidence that basal cell carcinoma with squamous atypia recurs and metastasises more often, so the UK dataset asks for it to be identified and treats it as high risk. The many other differentiations a basal cell carcinoma can show, pigmented, adenoid, keratotic, clear cell, granular, with eccrine, apocrine, sebaceous or follicular components, need not be recorded at all: they do not change what is done.

In practice most tumours are composite, containing low-risk and high-risk patterns at once. There is no evidence about what percentage or position of a high-risk pattern matters, so the UK rule is pragmatic: the overall risk status is read from the highest-risk pattern present, irrespective of percentage or location, and once a high-risk component is recorded the low-risk ones need not be.

## Fields

- Kind: Term
- Last checked: 2026-09-25
- Also known as: nodular basal cell carcinoma; superficial basal cell carcinoma; infiltrative basal cell carcinoma; infiltrating basal cell carcinoma; morphoeic basal cell carcinoma; sclerosing basal cell carcinoma; micronodular basal cell carcinoma; basosquamous carcinoma; fibroepithelial basal cell carcinoma; Pinkus tumour; fibroepithelioma of Pinkus; composite basal cell carcinoma; pigmented basal cell carcinoma; BCC subtype; BCC growth pattern; high-risk BCC

## Notes

- The classification cannot see the distinction the UK cares most about. ICD-O, the morphology coding system registries use, gives micronodular basal cell carcinoma no code of its own: it is a related term sharing 8097/3 with nodular, which is a low-risk pattern. Sclerosing and morphoeic share 8092/3 with infiltrating. So a registry coding from ICD-O alone cannot reliably tell a high-risk micronodular tumour from a low-risk nodular one, which is worth knowing before reading anything derived from registry morphology codes.
- Why the pattern is on the report at all when the treatment is an operation either way. Because it decides which operation, where it is done and by whom. The UK dataset is explicit that low-risk basal cell carcinomas can be treated in primary care by appropriately trained and accredited practitioners, and that all others must be treated in secondary care; and that high-risk tumours with involved margins, patients for Mohs surgery and immunocompromised patients go to the skin cancer multidisciplinary team (G123). A morphoeic tumour on a nose and a nodular one on a back are the same diagnosis and a different day.
- The one thing a growth pattern is not: a grade. Basal cell carcinoma is not graded. A proposal to divide it into differentiated and undifferentiated types had limited support and was not adopted, and the UK dataset records pattern and, where present, squamous differentiation, and nothing else of that kind (G123). If a report gives a grade for a basal cell carcinoma, it is answering a question the dataset does not ask.

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Basal-cell_carcinoma
- Royal College of Pathologists G123: dataset for histopathological reporting of primary cutaneous basal cell carcinoma, version 4, February 2019 (Slater and Barrett): https://www.rcpath.org/resourceLibrary/g123-dataset-basal.html
- Cancer Research UK: basal cell carcinoma: https://www.cancerresearchuk.org/about-cancer/skin-cancer/types/basal-cell-carcinoma
- Nasr et al., British Journal of Dermatology 2021;185(5):899 to 920: British Association of Dermatologists guidelines for the management of adults with basal cell carcinoma 2021: https://doi.org/10.1111/bjd.20524
- WHO Classification of Tumours Editorial Board: Skin tumours, 5th edition, volume 12 (IARC, Lyon, 2025), ISBN 978-92-832-4535-3: https://publications.iarc.who.int/Book-And-Report-Series/Who-Classification-Of-Tumours/Skin-Tumours-2025
- Elder, Massi, Scolyer and Willemze (eds): WHO Classification of Skin Tumours, 4th edition, volume 11 (IARC, Lyon, 2018): https://publications.iarc.who.int/Book-And-Report-Series/Who-Classification-Of-Tumours/WHO-Classification-Of-Skin-Tumours-2018
- Histopathology 2026;88:555 to 568: WHO classification of skin tumours, key updates in the fifth edition (open-access summary of what the 2025 volume changed): https://doi.org/10.1111/his.15562
- IARC and the International Association of Cancer Registries: ICD-O-3.2 morphology and behaviour codes (actinic keratosis 8070/0; Bowen disease 8081/2; keratoacanthoma a related term under 8071/3; micronodular basal cell carcinoma shares 8097/3 with nodular, and sclerosing or morphoeic shares 8092/3 with infiltrating): http://www.iacr.com.fr/index.php?option=com_content&view=category&layout=blog&id=100&Itemid=577

## Connected records

- terms: [Histology](https://onco.cc/terms/histology/), [How skin carcinoma is staged in Britain: UICC TNM, and why it is not the American system](https://onco.cc/terms/tnm-skin-carcinoma/), [Inherited syndromes that cause skin cancer: Gorlin syndrome and xeroderma pigmentosum](https://onco.cc/terms/inherited-skin-cancer-syndromes/), [Keratinocyte cancer (and why 'non-melanoma skin cancer' is being retired)](https://onco.cc/terms/keratinocyte-cancer/), [Mohs surgery](https://onco.cc/terms/mohs-surgery/), [Resection margins (R0 / R1 / R2)](https://onco.cc/terms/resection-margins/), [The subtype and grade on a cutaneous squamous cell carcinoma report](https://onco.cc/terms/cscc-subtype-and-grade/), [Tumour differentiation (well / moderately / poorly differentiated)](https://onco.cc/terms/tumour-differentiation/), [What makes a skin cancer high risk: the UK feature lists](https://onco.cc/terms/skin-cancer-high-risk-features/)
- cancers: [Basal cell carcinoma](https://onco.cc/cancers/basal-cell-carcinoma/), [Locally advanced and metastatic basal cell carcinoma](https://onco.cc/cancers/locally-advanced-bcc/), [Skin cancer (all types)](https://onco.cc/cancers/skin-cancer/)
- fronts: [Diagnostics & Biomarkers](https://onco.cc/fronts/diagnostics/)

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