Inflammatory carcinoma of the breast: not all breast erythema is mastitis

A 47-year-old premenopausal woman was referred to our institution due to a lump in her left breast, which she has been aware of for 2 months. She had no systemic symptoms and no relevant past medical history.

At physical examination, the patient’s left breast was enlarged, indurated, erythematous, warm and tender. The skin was thickened and edematous, with a "peau d'orange" appearance (Figure 1).

Mammograms of the left breast showed diffuse breast enlargement and increased density, skin thickening, a cluster of fine pleomorphic microcalcifications and enlarged axillary lymph nodes (Figure 2).

Ultrasound showed diffuse architectural distortion on all quadrants, overlying subcutaneous edema and enlarged axillary lymph nodes (Figure 3).

MRI revealed an enlarged left breast with diffuse edema, skin thickening and enhancement, asymmetric diffuse nonmasslike parenchymal enhancement, an irregular mass and multiple axillary, mediastinal and hilar lymphadenopathy. An initial rapid enhancement with washout curve was seen on the kinetics evaluation (Figure 4).

Two ultrasound-guided biopsies were performed, one from an area of architectural distortion in the upper quadrants, which revealed ductal carcinoma in situ, and another one from a left axillary lymphadenopathy, revealing carcinoma metastasis.

Additionally, a skin punch biopsy was performed, and the anatomopathological result showed a massive infiltration of the dermis by poorly differentiated/G3 NST invasive carcinoma with coexisting lymphatic embolization in the dermis.

The patient started neoadjuvant chemotherapy.

Background

Inflammatory breast cancer (IBC) is a rare subtype of breast cancer (2% to 5% of all breast cancers), typically occurring in women between the 4th to 5th decades [1]. A high body mass index is an independent risk factor for IBC. Possible risk factors are viral infections and chronic inflammation, younger age at first live birth, smoking and breastfeeding, although they need further investigation. Inherited genetic mutations and family history have demonstrated no association [2].

Clinical Perspective

Clinically, IBC mimics mastitis. Patients usually present with a rapid onset of symptoms [2]. The breast is usually enlarged, warm and tender, which may resemble inflammation. However, there isn’t a true inflammatory component in IBC, and systemic symptoms such as fever are absent, which helps to differentiate it from mastitis.

Another clinical finding that is frequently seen is the peau d'orange, which means “skin of orange”, describing a dimpled skin appearance caused by tumor emboli that obstruct dermal lymphatics [3, 4].

Imaging Perspective

Mammographic findings include diffuse enlargement of the breast, stromal coarsening, diffuse increased density, skin thickening, and nodal enlargement [5, 6]. Less commonly, multiple masses, pleomorphic calcifications or architectural distortion can be seen.

Ultrasound can be helpful in assessing a suitable site for biopsy [7].

Diagnosis of IBC using conventional imaging modalities such as mammography and ultrasound may be challenging because some features can resemble the inflammatory findings of a mastitis [7].

Magnetic resonance imaging (MRI) is the most accurate technique for the initial diagnosis of IBC and to evaluate the extent of the disease (including to search for occult disease in the contralateral breast). MR images also provide a baseline for comparison with subsequent follow-up images to assess treatment response [8, 9]. Common findings include extensive or segmental nonmasslike enhancement and diffuse skin thickening [6, 8, 10, 11]. A mass with irregular or spiculated margins may manifest with adjacent satellites, multiple masses, or nonmasslike enhancement [8, 9]. Kinetics typically show initial rapid enhancement with washout or plateau curves [9]. Findings of extraparenchymal disease include edema, enhancement or tethering of the pectoral muscle, which indicates possible tumor involvement, and diffuse cutaneous edema [10, 12].

The main differential diagnoses are infective mastitis and locally advanced invasive breast carcinoma. To confirm the diagnosis, histological diagnosis of malignancy is required. In cases where an image-guided biopsy cannot confirm the diagnosis, a skin punch biopsy may be indicated [2]. Histologically, dermal lymphatic invasion is pathognomonic of IBC, but is not required for diagnosis [2].

Outcome

Unlike other types of breast cancer for which surgery is the first modality of treatment, chemotherapy or radiation therapy before surgery is the gold standard. IBC is an invasive aggressive disease with a high rate of metastasis at diagnosis, and a 5-year survival rate of 25%-50% [13, 14].

Take Home Message / Teaching Points

IBC is an invasive aggressive disease with a high rate of metastasis at diagnosis.

Both histological diagnosis of malignancy and clinical evidence of inflammatory disease are required to confirm the diagnosis of IBC.

Chemotherapy or radiation therapy before surgery is the gold standard treatment.