Tubular adenoma of the breast: radiological and ultrasound findings

http://dx.doi.org/10.1590/0100-3984.2017.0062 Lívia de Oliveira Antunes1, Rafael da Silveira Borges1, Wania Vasconcelos de Freitas1, Simone Rachid de Souza2, Diogo Goulart Corrêa3 1. Hospital Casa de Portugal, Rio de Janeiro, RJ, Brazil. 2. Hospital Federal do Andaraí, Rio de Janeiro, RJ, Brazil. 3. Hospital Casa de Portugal e Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ, Brazil. Correspondence: Dra. Lívia de Oliveira Antunes. Rua Gustavo Sampaio, 88, ap. 902, Leme. Rio de Janeiro, RJ, Brazil, 22010-010. E-mail: li_antunes@hotmail.com. and the abdomen/pelvis (in 20%). However, within the cervicofacial region, the maxilla is the least commonly affected site, accounting for only 0.5–9.0% of cases in the head and neck. Bone involvement is even more rare, osteomyelitis being sporadic or secondary to infection at primary sites. Risk factors for cervicofacial involvement include inadequate oral hygiene, trauma to the oral mucosa, chronic tonsillitis, otitis, mastoiditis, and osteonecrosis induced by radiotherapy or bisphosphonates. It is of note that, different than what is observed for the other affected sites, cervicofacial infection with Actinomyces sp. occurs more commonly in patients who are immunocompetent. In its acute form, actinomycosis usually manifests as edema of the soft tissues, together with the formation of masses and abscesses, evolving, chronically, to dissemination of the infection to the adjacent soft tissues, then the fascial planes, externalizing itself through fistulas of the skin and paranasal sinuses. However, it is rarely seen in combination with osteomyelitis. On computed tomography, actinomycosis appears as a mass with ill-defined borders, soft-tissue density, and contrast enhancement, together with fluid collections and fistulas. The differential diagnosis includes fungal ulcers, carcinoma, idiopathic midline granuloma, and osteomyelitis of the maxilla caused by other germs. In the histopathological analysis, hematoxylineosin staining reveals chronic abscess with polymorphonuclear leukocytes, granulation tissue and fibrosis, Grocott’s staining revealing colonies of bacilli forming “sulfur granules”, which represent tangled filaments of Actinomyces, present in abscesses, exudates of the sinus tract, or tissues infiltrated by the lesions. Penicillin G is the drug of choice for the treatment of actinomycosis, requiring long courses of antibiotic therapy. Surgical management is reserved for the drainage of bulky abscesses, marsupialization of chronically infected sinus tracts, excision of fibrotic lesions, and debridement of necrotic bone tissue. Therefore, despite its rarity, it is important to bear actinomycosis of the maxilla in mind as a differential diagnosis, mainly in cases of aggressive lesions of the mouth related to the abovementioned predisposing factors.

and the abdomen/pelvis (in 20%). However, within the cervicofacial region, the maxilla is the least commonly affected site, accounting for only 0.5-9.0% of cases in the head and neck. Bone involvement is even more rare, osteomyelitis being sporadic or secondary to infection at primary sites (2)(3)(4) . Risk factors for cervicofacial involvement include inadequate oral hygiene, trauma to the oral mucosa, chronic tonsillitis, otitis, mastoiditis, and osteonecrosis induced by radiotherapy or bisphosphonates. It is of note that, different than what is observed for the other affected sites, cervicofacial infection with Actinomyces sp. occurs more commonly in patients who are immunocompetent (2,3) .
In its acute form, actinomycosis usually manifests as edema of the soft tissues, together with the formation of masses and abscesses, evolving, chronically, to dissemination of the infection to the adjacent soft tissues, then the fascial planes, externalizing itself through fistulas of the skin and paranasal sinuses. However, it is rarely seen in combination with osteomyelitis (3) .
On computed tomography, actinomycosis appears as a mass with ill-defined borders, soft-tissue density, and contrast enhancement, together with fluid collections and fistulas. The differential diagnosis includes fungal ulcers, carcinoma, idiopathic midline granuloma, and osteomyelitis of the maxilla caused by other germs (5) . In the histopathological analysis, hematoxylineosin staining reveals chronic abscess with polymorphonuclear leukocytes, granulation tissue and fibrosis, Grocott's staining revealing colonies of bacilli forming "sulfur granules", which represent tangled filaments of Actinomyces, present in abscesses, exudates of the sinus tract, or tissues infiltrated by the lesions (3,6) .
Penicillin G is the drug of choice for the treatment of actinomycosis, requiring long courses of antibiotic therapy. Surgical management is reserved for the drainage of bulky abscesses, marsupialization of chronically infected sinus tracts, excision of fibrotic lesions, and debridement of necrotic bone tissue (2) . Therefore, despite its rarity, it is important to bear actinomycosis of the maxilla in mind as a differential diagnosis, mainly in cases of aggressive lesions of the mouth related to the abovementioned predisposing factors.  Figures 1B and 1C), corresponding to the lesion observed on ultrasound. A percutaneous core biopsy was performed ( Figure  1D), the histopathological analysis of which showed tubular adenoma of the breast, consistent with the radiological and ultrasound findings. Therefore, it was recommended that the patient undergo another ultrasound examination in six months and be followed in the breast disease department.
Tubular adenoma of the breast is a rare benign epithelial tumor of the breast that has not been widely studied; the World Health Organization defines it as a "benign, usually round, nodules formed by a compact proliferation of tubular structures composed of typical epithelial and myoepithelial cell layers" (1,2) .
Although four cases of malignant transformation of tubular adenoma have been reported in the literature, studies indicate that there is no high risk for carcinoma (1) . Tubular adenoma accounts for 0.13-1.7% of all benign neoplasms of the breast (3) . Although the size of the tumor ranges from 1 cm to 7.5 cm, it rarely exceeds 5 cm (4) . The vast majority of cases are in young women, and the disease is much more rare in postmenopausal women, 90% of the patients being under 40 years of age (mean, 31 years). Nevertheless, there have been reports of its occurrence in males. It has not been found to be associated with oral contraceptive use or pregnancy (4,5) . It is considered a variant of fibroadenoma, appearing in the same clinical context and with overlapping imaging characteristics (6) . It can be difficult to make the histological differentiation between tubular adenoma and fibroadenoma if the tubular adenoma has a relatively abundant stromal component or the fibroadenoma shows significant proliferation of small ducts (1) .
Clinically, tubular adenomas of the breast can be asymptomatic, occasionally being detected on mammography or physical examination as a palpable nodule that gradually increases in size (4) . On mammography and ultrasound, these tumors have the appearance of noncalcified fibroadenomas (7) . On mammography, the lesions typically appear as well-circumscribed nodules, with no evidence of calcifications. However, in older patients, punctate or irregular calcifications can be observed, findings that justify a biopsy to exclude malignant neoplasm of the breast. Occasionally, mammography shows lesions with ill-defined margins. On ultrasound, the tumors are generally described as hypoechoic, well-circumscribed nodules. Noncalcified tubular adenomas generally have a relatively homogeneous internal texture and may have posterior acoustic reinforcement (4) . Other differential diagnoses that should be included are ductal adenomas, lactating adenoma, gestational hyperplasia, and ductal carcinoma (8) . Sengupta et al. (3) , analyzing 32 confirmed cases of tubular adenoma, concluded that, although radiological and cytological studies can distinguish between benign and malignant lesions, the final diagnosis depends on the histopathology (3) .