Nodular Fasciitis of the breast

Nodular breast fasciitis is a benign, small, fibrous cellular growth, which often grows as a mesenchymal (stem cell) reaction to an injury.

Other common names for the condition are:-

subcutaneous pseudosarcomatous fibromatosis
pseudosarcomatous fibromatosis

They tend to grow on the subcutis, which is a layer of connective tissue beneath the dermis of the skin. As such, nodular fasciitis is more of a ‘skin’ issue and not really related to breast cancer at all.

What causes nodular fasciitis?

It’s a skin thing, just below the skin dermis layer, but nobody knows exactly WHY the fibrosis grows thick like a lump.

In rare instances, nodular fasciitis may develop on the breast or be discovered in a screening mammogram, but this can likely be due to trauma or injury. The development of nodular breast fasciitis can ‘resemble’ malignant cell processes, so really it is an issue of a proper, benign differential diagnosis.

Breast nodular fasciitis may grow quickly

Nodular fasciitis can grow anywhere, particularly on the neck, trunk, and the upper extremities. They are small lesions but they grow very rapidly, usually over just a few weeks. Nodular fasciitis can occur at any age but are most common in young adults with a peak age of 40 years. When palpable, they are often described as ‘elastic-hard’ and ‘movable’.

Diagnostic imaging and histological characteristics of Nodular Fasciitis

Histologically, a nodular fasciitis lesion will tend to show characteristic ‘spindle-like’ cells, and many of these proliferating spindle cells will have features of myofibroblasts.

The ‘spindle’ appearance of these cells bears a close resemblance to spindle cell carcinoma, and that it why they are sometimes misdiagnosed.

In addition to the spindle cells, nodular fasciitis will often feature wide bands of collagen and vascular (blood vessel) proliferation. Lymphocytes are also frequently encountered. (Lymphocytes are a type of white blood cell that functions as antibodies against injury and infection).

Nodular fasciitis also can show a certain degree of cell mitosis and ‘cellularity‘ (large amounts of cells and many different types of cells), which can also raise suspicions of malignancy, even though they are benign.

However, if the lesion shows cells which are very large and with atypical hyperchromatic nuclei, that would suggest a more malignant situation and possible association with breast cancer.

Nodular fasciitis of the breast can be misleading on an X-ray

Radiologically, nodular fasciitis can be a bit confusing initially as they can show ‘infiltrative’ margins. (Smooth, well-defined margins are most commonly associated with benign growths, irregular margins are more suspicious of malignancy).

Nodular fasciitis tumors can show spiculated margins, but they tend not to have calcification. Sonogram can also be a bit vague, and nodular fasciitis will tend to show a relatively homogeneous hypoechoic, solid mass with a border often obscured by normal tissues.

Sometimes MRI is also used for imaging studies, which can give a very good indication of the irregular shape of the lesion, but still can not rule of malignancy.

Biopsy is almost always necessary. Essentially harmless, these lesions are often just let be, unless they grow very quickly or begin to show other unexpected changes on follow-up breast evaluations and breast cancer screenings.

A couple of Q & A’s

What about recurrence after Surgical Excision?

Sometimes, not always, it can return in the scar after removal.

Is it a Genetic Condition?

Yes, it is possible, but usually not.

What are the symptoms of Nodular Fasciitis?

A thickening of the skin
a lump
a raised streak below the skin
Sometimes pain in the affected area

References

Wirman JA. Nodular fasciitis, a lesion of myofibroblasts. An ultrastructural
study. Cancer. 1976;38:2378 2389.
Bernstein KE, Lattes R. Nodular (pseudosarcomatous) fasciitis, a nonrecurrent
lesion. Cancer. 1982;49:1668–1678.
Iwatani, T., Kawabata, H., Miura, D., Inoshita, N., Ohta, Y., Nodular
fasciitis of the breast . Breast Cancer, aug. 2009.
Birdsall, SH., Shipley, JM., Summersgill, BM., Black, AJM., Jackson, P.,
Kissin, MW., Gusterson, BA. Cytogenetic findings in a case of nodular fasciitis
of the breast. Cancer Genetics and Cytogenetics, Volume 81, Issue 2, June
1995, Pages 166-168
Maoko, O., Takayuki, O., Masaki, K., Yoichi, T., Naoya, G., Kenichi, S.,
A case of nodular fasciitis of the breast resected by endoscopic surgery.
Journal Title;Journal of Japan Surgical Association., Vol. 65:1. Page 42-45.
Harvey, S., Denision, C., Lester, S., DiPiro, P., Smith, D., Meyer, J.,
Fibrous Nodules Found at Large-Core Needle Biopsy of the Breast: Imaging
Features. Radiology, May 1999 volume 211, 535-540.
Rosen PP. Benign mesenchymal neoplasms In: Rosen’s breast pathology. Philadelphia,
Pa: Lippincott-Raven, 1996.
Dahlstrom, Je. Buckingham, Jm. Bell, S. Jain, S., Nodular fasciitis of
the breast simulating breast cancer on imaging . Australasian Radiology,
Volume 45, Number 1, February 2001 , pp. 67-70(4)