Post-burn duct carcinoma breast: An unusual case report.

Malignancies arising from burn scars though rare are well documented in the literature; squamous cell carcinoma is the most common burn scar neoplasm, and adenocarcinoma is an extremely uncommon and rarely reported tumor in these scars. We hereby report a case of a young woman who presented with a rapidly growing lump in a scar in the mammary region that sustained severe burns 20 years back. It was diagnosed as duct carcinoma breast on cytology and later confirmed on histopathology and immunohistochemistry. The case mandates regular follow-up of patients with post-burn scars, and any lump arising in that region should be promptly investigated.

Introduction

Malignancies arising in burn scars (BS) are rare, but well documented in the literature.[1234567] Squamous cell carcinoma is the most common type, others being basal cell carcinoma, malignant melanoma and rarely sarcomas.[123] Adenocarcinoma (AC) is an extremely rare malignancy arising in BS with only four cases reported in the literature till date.[148] There have been no previous reports of infiltrating duct carcinoma (IDC) arising in BS. We report a rare case of a young woman who developed duct carcinoma breast in burn scar after 20 years of thermal burn injury to that region.

Case Report

A 27-year-old woman presented with a rapidly growing lump in the right chest wall for 3 months. She had sustained thermal burns 20 years back, involving the right side of the chest wall, arm and trunk. The burns were left to heal secondarily and skin grafting was not done. On examination, the BS involved the right mammary area, axilla, arm and upper back. Because of severe scar contractures, the upper arm was adherent to the trunk [Figure 1a]. The right breast was completely deformed. Underneath the burn scar, there was a large, firm lump measuring 10 × 8 × 6 cm in the right mammary region. The lump was adherent to the underlying chest wall but the overlying skin was free. The right axilla could not be palpated due to severe scar contractures. A firm, mobile lymph node measuring 1.5 × 1 × 1 cm, was palpable in the right supraclavicular region. Left breast and axilla were unremarkable.

Figure 1

(a) Clinical photograph showing extensive burn scar involving right mammary area, chest and arm; (b) FNA smears from breast showing malignant epithelial cells arranged in clusters and glandular pattern (Giemsa stain, ×300); (c) Biopsy from breast lump showing features of infiltrating duct carcinoma breast (H and E, ×300)

The patient was referred for fine needle aspiration cytology (FNAC) from the lump and supraclavicular lymph node which was performed as per the standard technique. FNA from the mammary lump yielded thick yellowish aspirate, which was processed as air-dried, Giemsa stained smears and a part of it was processed for cell-block preparation. FNA smears showed moderate cellularity, comprising singly scattered and loosely cohesive clusters of round to oval cells; forming a glandular pattern at places [Figure 1b]. The cells showed moderate pleomorphism with high nuclear-cytoplasmic ratio, coarse chromatin, prominent 1-2 nucleoli and moderate amount of pale blue cytoplasm. The background was necrotic. Immunocytochemistry for HER-2/neu was performed on the cell-block sections, the cells showed focal weak positivity for the marker. FNAC from the supraclavicular node revealed similar features, suggestive of metastasis. Thus a cytological diagnosis of duct carcinoma breast was suggested.

A trucut biopsy from the lump [Figure 1c] revealed solid nests and tubular formations of atypical round to oval cells, with moderate amount of cytoplasm, coarse chromatin with 1-2 prominent nucleoli and high mitotic activity (1-2/hpf). There was marked desmoplastic reaction in the surrounding stroma. On immunohistochemistry (IHC), few tumor cells stained positive for HER-2/neu. Thus histological features and IHC were compatible with a high-grade IDC (NOS, grade 3). The patient declined surgery and was lost to follow-up.

Discussion

Cancers arising in old BS are rare. The average latent period for development of a post-burn malignancy is 30 years.[27] Squamous cell carcinoma is the commonest tumor arising in old BS (71%) followed by basal cell carcinoma (6%), malignant melanoma (5%) and sarcomas (4%).[2] There are rare case reports of malignant fibrous histiocytoma, dermatofibrosarcoma protuberans, pleomorphic liposarcoma and verrucous carcinoma in post-burn patients.[2367] Adenocarcinoma arising in post-BS is extremely rare. An extensive literature search revealed four cases of AC arising in burn scars, out of which one was a metastatic AC in a burnt arm from a lung primary, while three were reported as AC arising in the previously burnt breast/mammary area.[148] However none of these was reported as IDC breast. To the best of our knowledge, this is the first case of an IDC breast developing in post-BS. The published literature provides very little information about the possible link between old thermal scars and development of duct carcinoma breast.

A review of literature suggests that severe burns which are allowed to heal without skin grafting (as in the present case), are especially prone to develop cancer. Malignant transformation rarely occurs in grafted skin, and hence rapid epithelization and prompt skin grafting should be promoted.[47]

Various proposed theories to explain the etiopathogenesis of tumors in BS include chronic irritation (Virchow), misplaced epithelial cells (Ribbet), release of toxins by autolysis and heterolysis from tissue (Treves and Pack), repeated trauma and loss of skin elasticity resulting in ulceration, hence provoking malignant transformation (Gibbin).[12347] Bostwick et al,[3] stated that the obliterated vascular and lymphatic channels in BS restricts drainage, making the scars privileged sites for unhindered immunological activation and tumor growth.

For a tumor to qualify as a post-burn malignancy, it must fulfil the ‘Ewing's postulates’ that include five criteria: (a) evidence of a burn scar, (b) tumor within the boundaries of the scar, (c) no previous tumor in that location, (d) tumor histology compatible with the cell types found in the skin scar, (e) an adequate interval between burn injury and tumor development.[2] The present case fulfils these postulates, and hence qualifies as a malignancy arising in a BS rather than just a coincidental finding.

Embryologically, breast is a modified sweat gland organ. The occurrence of IDC breast in post-burn scar suggests that the potential for malignant change exists not only in the scar and subepithelium; but also in adnexal elements and adjacent subcutaneous connective tissue.[1] Many factors can lead to delayed detection of post-burn breast carcinoma which include difficulty in examining the breast because of altered breast structure due to scarring, tumor concealed under a thick contracted scar and detection at a late stage due to unusually rapid growth in these high grade tumors.[4]

Conclusions

To conclude, although these tumors are very rare, yet the possibility of post-burn infiltrating duct carcinoma should be kept in mind, in patients who sustain burns in the chest/mammary region. Prompt skin grafting should be promoted to minimize the risk of malignant tumors in severely burnt patients. These patients need close follow-up and any lump developing in the region of the scar requires a prompt FNAC/biopsy to determine the nature of the lesion.