Diabetic Fibrous Mastopathy of the Breast

Diabetic fibrous mastopathy is a condition characterized by the development of one or more breast lumps as a result of a long standing association with type I (insulin dependent) diabetes. (Diabetic fibrous mastopathy usually occurs in women with ‘juvenile-onset‘ diabetes) It mostly effects premenopausal women, but has been known to affect men as well.

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In terms of it’s clinical and radio graphic appearance, diabetic fibrous mastopathy is virtually indistinguishable from breast cancer, so it is a welcome differential diagnosis when confirmed histologically. Other terms sometimes used for diabetic fibrous mastopathy include diabetic fibrous breast disease, lymphocytic mastitis, and lymphocytic mastopathy.

Diabetic fibrous mastopathy is a reactive breast lesion, and is mainly composed of a combination of both fibrotic and inflammatory elements.


Develops in 10% -15% of women with type I diabetes

Essentially, a diabetic fibrous mastopathy lesion is a connective tissue overgrowth, usually with vasculitis, and some proliferation of duct epithelium. These kinds of breast changes are not typically associated with any increased risk of breast cancer.

Breast lesions of all kinds occur in about one-half of all female patients with type I diabetes, and diabetic fibrous mastopathy is estimated to develop in about 13% of women with type I diabetes. These tumors take a long time to develop, however, on average 20 years after the first onset of this disease.

Diagnosis of breast diabetic fibrous mastopathy

Usually, diabetic fibrous mastopathy is discovered by a woman herself as an ill-defined, painless and immobile lump. It is brought to the attention of a family physician, who initiates breast cancer screening procedures. Mammograms are often inconclusive, but breast ultrasound tends to reveal a lesion highly suspicious of breast cancer.

A biopsy is usually taken to confirm or otherwise clarify the suspicious of breast cancer, and it can be a few anxious days of waiting until the histological analysis confirms a differential diagnosis of diabetic fibrous mastopathy and not breast cancer. Diabetic fibrous mastopathy lesions may be solitary, but present multiply about 65% of the time.

Masses may appear in a wide range of sizes. They can be palpable or only discovered mammographically, and they can occur in any breast quadrant, although they do have a propensity to develop in the subareolar region.


Mammographical features of breast diabetic fibrous mastopathy tend to be unremarkable, due to the presence of unusually dense breast tissue. The typical radiological finding is one of very dense glandular tissue, or as an ill-defined mass which appears as an asymmetry on an irregular lesion, often obscured by dense breast tissue.

The breast X-ray above shows areas of very dense breast parenchyma and one focal area of very high density (likely the site of a lump).

Sonogram findings for diabetic fibrous mastopathy ‘appear‘ suspicious for malignancy

Ultrasonography, however, will tend to show an irregular hypoechoic mass, very dense, with very obvious posterior acoustic shadowing, often with ill-defined margins. These findings would be considered highly suspicious for malignancy.

It is not unusual in diabetic breast fibrous mastopathy for multiple areas of acoustic shadowing to appear, and in either breast. The amount of shadowing found in a diabetic fibrous mastopathy lesion is very marked, even greater than one finds with most breast cancers. However, a biopsy is almost always needed to confirm or otherwise differentiate the diagnosis.


Histological aspects of breast diabetic fibrous mastopathy

Typically, on histological evaluation of breast diabetic fibrous mastopathy one finds a dense keloid-like fibrosis. There is typically little or no adipose tissue, or cellular materials. What one usually finds instead is periductal, lobular or perivascular lymphocytic infiltration, predominately with B cells (the inflammatory aspect of the lesion).

One often finds lobular atrophy, and epithelioid fibroblasts embedded in dense fibrous stroma. In the cytological image of diabetic fibrous breast mastopathy below, one notes an extensive perivascular infiltration of mature lymphocytes, and very dense fibrous stroma.


Causes of diabetic fibrous mastopathy of the breast

The exact cause of diabetic fibrous mastopathy is unknown, and only speculative. It is generally thought to be the result of some sort of auto-immune reaction. It has been proposed that exogenous insulin might lead to the development of diabetic mastopathy tumors through an inflammatory or immunologic reaction to insulin.

Perhaps they are the result of extra cellular matrix expansion secondary to increased collagen production and decreased degradation. This sometimes happens to connective tissues as a result of hyperglycemia.

Treatment and management of diabetic fibrous mastopathy of the breast

Diabetic breast fibrous mastopathy is neither a malignant nor pre-malignant condition and should therefore be treated conservatively. Once the diagnosis is confirmed, these masses are usually just left alone. If a patient is younger, yearly ultrasound examinations are probably sufficient. Older patients should probably have yearly mammogram, ultrasound, and clinical examinations.

But since the number and size of diabetic fibrous mastopathy lesions tends to increase as a patient ages, fine needle or possibly core biopsies are often recommended for any new lesions, just to ensure they are not malignant breast cancer lesions. Surgical removal of diabetic fibrous mastopathy tumors might be an option, but this would be a choice the woman and physician would have to make.

The recurrence rate following surgical removal tends to be rather high at around 32%, and usually within five years of the surgery. These breast lumps do not go away on their own unfortunately, but as there is no evidence to support development of breast cancer from diabetic fibrous mastopathy, surgery should probably be avoided.

For further reading, I suggest you visit this page which has some information on fibrocystic disease of the breast.


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