Last revised by Dr Ammar Ashraf on 28 Aug 2022

Gigantomastia (also known as macromastia or mammomegaly) is the term employed when there is massive breast enlargement. It is often associated with pregnancy. It may be rarely unilateral.

Gigantomastia is a very common condition characterized by proliferation of either breast fatty tissue or glandular tissue or both, resulting in rapid increase in breast size over a rather short period of time.

It has been defined as excessive breast tissue greater than 1.5 Kg (range=0.8-2.0 Kg) or at least 3% of the body weight; however, still there is no global agreement about its definition 6-8.

It may be seen in about one of every 100,000 pregnancies.

It has been classified in to three types; type 1 is idiopathic and is related to the marked breast overgrowth in females with BMI >30 (type 1a) or BMI<30 (type 1b), type 2 is caused by the hormonal imbalance, related to the puberty (type 2a) or pregnancy (type 2b) and type 3 which is secondary to the drugs 6,7.

It has been described in conjunction with hypercalcemia, hyperprolactinemia, deranged liver function tests and certain autoimmune diseases like Hashimoto thyroiditis, rheumatoid arthritis (RA), myasthenia gravis, systemic lupus erythematosus (SLE) and psoriasis 6,7,9,10.

Its exact etiology is unknown however it is believed to be due to an abnormal response to pregnancy-related hormonal stimulation. Significant enlargement of the breasts may cause tissue necrosis, ulceration, infection and hemorrhage, which may be life-threatening. The diagnosis is based on the clinical findings and in normal circumstances radiologic studies are required only if there is an underlying disorder.

It can occur with peripubertal breast hypertrophy, juvenile gigantomastia, obesity-related breast hypertrophy or as a complication secondary to pregnancy-related gland hypertrophy. Some authors believe macromastia to be associated with an increased risk of malignancy.

Medical treatment is with bromocriptine administration; however surgical intervention may be required if the disorder continues to progress. The usual surgical management involves reduction mammoplasty. The resected specimen is sent for histological evaluation to exclude malignancy.

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Cases and figures

  • Case 1: gigantomastia with breast lipoma
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  • Case 2: gigantomastia (type 1a)
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