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Hamartomas of the Breast: A Mimic of Fibroadenoma and Cytological Pitfall

case Hamartoma is a rare benign lesion of the breast, accounting for around 4.8% of all benign breast lesions.[1,2] Pathologically, hamartomas lack a distinctive feature. It is important to recognize this poorly recognized benign lesion as clinically and cytologically hamartoma may mimic other benign entities.[3] We present here a case of a hamartomas of the breast in an 18 year old female which was reported as fibroadenoma radiologically and on fine needle aspiration cytology (FNAC).

Subsequently, excisions of bilateral breast swellings were done. Grossly, two globular grey white soft tissue masses were received, each measuring 2 × 1.8 × 1.5 cm. Cut surface was homogenous grey-white. On histopathology, sections showed a well circumscribed lesion, showing terminal ductal lobular units arranged in a disorganised architecture, along with dense hyalinized stroma admixed with fibroadipose tissue [ Figure 1d-f]. Based on these histopathological findings, a final diagnosis of hamartoma of the breast was given.

dIscussIon
The word "hamartoma" was first coined by Arrigoni et al. [4] in 1971. The word is Greek in origin and means "bodily defect". Hamartomas are benign non-neoplastic lesions, composed of disorganised mixture of elements which are endogenous to a particular site. [1] Pathologically, breast hamartomas are composed of admixture of benign epithelial elements, fibrous and fatty tissue. The exact pathogenesis for development of breast hamartoma is still unknown, but it is said to be a developmental anomaly. They are commonly observed in premenopausal women, but they are known to occur in as young as teenagers. [1] The present case was that of an 18 year old female. Clinically, they present as painless, mobile soft to firm swelling, mimicking a fibroadenoma, [5] which was also the scenario in the present case.
On ultrasound, hamartomas are well circumscribed lesions with a smooth outer border and hyperechoic or heterogenous internal echogenicity. [6] Sometimes, they might appear to be homogeneously dense if rich in fibrous tissue, mimicking a fibroadenoma radiologically. Cytological techniques, although useful in diagnosing most breast lesions; may not be able to differentiate hamartomas from other benign entities like fibroadenoma. [3][4][5][6] Grossly, hamartomas are round to oval masses and can be as large as 20 cm in size. The cut surface may resemble that of normal breast parenchyma or fibroadenoma, depending upon the consistencyof the lesion. [1] Originally, hamartomas were defined as clinically discrete nodules which are composed of variable amount of epithelial tissue in a fibrofatty stroma. [4][5][6][7] The presence of lobules within a fibrotic stroma that surrounds and extends to between individual lobules and also obliterates the interlobular specialised loose stroma, is characteristic of hamartomas. However, this feature may also be seen in sclerosing lobular hyperplasia. The absence of adipose tissue in stroma and frequent association with fibroadenoma can help differentiate between sclerosing lobular hyperplasia and hamartoma. [3][4][5]7] Adipose tissue in the stroma of hamartomas is commonly reported. In most studies, adipose tissue is present in more than 90% of the cases, although volume of adipose tissue is generally

Hamartomas of the Breast: A Mimic of Fibroadenoma and
Cytological Pitfall 10-20% of the lesion volume. [7] In the present case also, adipose tissue was seen within the stroma, clinching towards the diagnosis of hamartoma. Pseudo-angiomatous stroma, epithelial hyperplasia and cystic changes with or without concomitant apocrine metaplasia are also a common feature of breast hamartoma. [5][6][7] However, these changes were not observed in the present case. Other rare features have also been described in the literature, which include microcalcification, myoid differentiation, stromal edema and stromal giantcells. [4][5][6][7] The accurate diagnosis of hamartoma is important because of problems of recurrence, which actually represent multifocality as true recurrence is not known in a hamartomatous lesion. Multiple breast hamartomas are also associated with Cowden syndrome which is also known as Multiple Hamartoma syndrome. Genetic data is in breast hamartomas is limited. However, genetic alterations involving chromosomal regions 12q12-15 and 6p21 have also been described in literature. [1] Hamartomas of breast are rare, composed of normal breast components including glandular, fatty and fibrous tissue in varying proportions. It is under-diagnosed and often under-reported, as it is often missed on radiology as well as on FNAC. The pathologist needs to be aware of this entity; and whenever fibrous tissue within the lobules, or fibrous tissue and fat in the stroma is seen, it should clinch towards the possibility of a hamartoma.

Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient (s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship
Nil.

Conflicts of interest
There are no conflicts of interest.