Introduction

Rosai–Dorfman disease is a rare disorder caused by benign proliferation of histiocytes and thus also called sinus histiocytosis with massive lymphadenopathy [1]. It is typically known to involve lymph nodes but can also involve extra nodal sites in up to 23% patients [2].

Breast involvement is extremely rare with only 17 cases reported in English literature [1]. Most cases have been discovered on screening mammograms [3, 4]. Rosai–Dorfman disease of breast mimics malignancy on mammogram and ultrasound [3, 4], thus leading to surgical excision in most cases [5]. As in this case, in spite of a diagnosis of benign lymphoid process on fine-needle aspiration, wide local excision was done on clinical and radiological suspicion of malignancy.

Case presentation

A 21-year-old female came with complaints of lump in right breast for 2 years with recent progressive increase in size. No history of trauma or lactation was present. No family history of breast cancer was noted. On examination, palpable irregular superficial lump in upper outer quadrant with associated bluish red discoloration of skin and ecchymosis (Fig. 1a) was noted.

Fig. 1
figure 1

a The clinical image of the lesion shows a superficial lump with bluish red discoloration. b Right craniocaudal view and c right mediolateral view show a non-circumscribed irregular high-density lesion (yellow circle) with associated overlaying skin thickening (white arrow). d Zoomed image of the lesion shows skin thickening overlaying the lesion

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Patient was advised breast ultrasound and referred to a breast surgeon.

Ultrasound of the lump showed a non-circumscribed irregular heteroechoic lesion in upper outer quadrant at 10–11 o’clock in subcutaneous plane (Fig. 2a). This lesion was seen abutting the skin with overlying significant skin thickening. Doppler ultrasound showed avid internal vascularity with feeding vessel traced from a branch of internal mammary artery (Fig. 2b,c). Right axilla showed few lymph nodes with preserved fatty hilum (Fig. 2d).

Fig. 2
figure 2

a Grey scale ultrasound of the of the breast shows a non-circumscribed irregular heteroechoic lesion in subcutaneous plane. The lesion closely abuts the skin with overlying significant skin thickening. b, c Color flow and Doppler ultrasound show avid internal vascularity. d Right axilla ipsilateral axillary lymph nodes with preserved fatty hilum

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On the suspicion of malignancy digital mammography of the right breast was done. Right craniocaudal view (Fig. 1b) and right mediolateral view (Fig. 1c) showed a non-circumscribed irregular high-density lesion with associated overlying skin thickening (Fig. 1d) (white arrow). This was followed with MRI that showed a circumscribed irregular T1 hypointense (Fig. 3a), T2/STIR hyperintense (Fig. 3b) lesion in upper outer quadrant at 10–11 o’clock position, closely abutting the skin (white arrows) with associated overlaying skin thickening in right breast. Lesion showed DWI restriction (Fig. 3c). On maximum-intensity projection images (Fig. 3d), large feeding vessels arising (white arrowhead) from internal mammary artery (white arrow) and lateral thoracic artery were seen. On T1C, the lesion showed rapid contrast uptake which progresses to intense heterogeneous enhancement (Fig. 3e–h). Considering the above characteristics, the possibility of low-grade angiosarcoma was considered more likely with hemangioma as other possibility.

Fig. 3
figure 3

MRI of breast showed a a circumscribed irregular T1 hypointense, b T2/STIR hyperintense lesion in upper outer quadrant at 10–11 o’clock position, closely abutting the skin (white arrows) with associated overlaying skin thickening. cLesion shows DWI restriction. d On maximum-intensity projection images, large feeding vessels arise (white arrow head) from internal mammary artery (white arrow). e T1 sagittal contrast shows homogenously enhancing lesion in the upper quadrant. f T1 contrast early phase shows contrast uptake. g, h Enhancement progresses to intense heterogeneous enhancement in later phases

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Due to highly vascular nature of the lesion, fine-needle aspiration of the lesion was done, which showed lymphocytes and occasional histiocytes, suggestive of lymphoid process (Fig. 4a,b).As were equivocal findings and high clinical as well as radiological suspicion, surgical wide local excision (Fig. 4c) was performed and sent for histopathological analysis.

Fig. 4
figure 4

a Cytology image showing fibrocollagenous tissue in a background of lymphocytes (H&E ×200). b Cytology image showing reactive lymphocytes and histiocytes in the background (H&E ×400). c Intraoperative picture shows a linear incision in the lateral mammary fold and excised specimen placed on the breast. d On gross examination, the specimen was firm, ill-circumscribed grey tan lesion

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On gross examination, the specimen revealed a firm, ill-circumscribed grey tan lesion (Fig. 4d). Histologically, the lesion had characteristic accumulation of histiocytes with enlarged round to oval hyperchromatic nuclei and abundant cytoplasm (Fig. 5a,b). Few histiocytes displayed a phenomenon of emperipolesis, which was seen engulfing the inflammatory cells and it is characteristic of the said disease (Fig. 5b). On immunohistochemistry, these histiocytes showed positivity for S-100 (Fig. 5c) and CD 68 (Fig. 5d) confirming the diagnosis of Rosai–Dorfman disease.

Fig. 5
figure 5

a Histiocytes with enlarged, round-to-oval hypochromatic nuclei and abundant eosinophilic cytoplasm admixed with lymphocytes and a prominent lymphoid collection (H&E ×400). b Histiocytes engulfing lymphocytes and red blood cells (emperipolesis) (H&E ×400). c CD 68 positivity in the cytoplasm of the histiocytes (IHC ×400). d S100 positivity in the cytoplasm of the histiocytes (IHC ×400)

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Final diagnosis was reached only after the characteristic histopathological and immunohistochemical findings.

Wide local excision was done on suspicion of malignancy clinically and on imaging. Whole body examination along with abdominal, neck and bilateral axillary ultrasound was performed. It did not reveal any other similar lesions. Computed tomography was avoided in view of excessive radiation and young age of the patient.

Patient is advised to be kept on close yearly USG breast, abdomen and neck along with 2 yearly CT surveillance in view of young age of the patient.

Discussion

Rosai–Dorfman disease is a rare disorder caused by benign proliferation of histiocytes and thus also called sinus histiocytosis with massive lymphadenopathy [1]. It is typically known to involve lymph nodes but can also involve extra nodal sites in up to 23% patients, with breast involvement being extremely rare [2].

Most patients present as benign lump in breast, but many cases have been diagnosed in screening mammograms in asymptomatic women [2,3,4]. Radiological features are variable. It may present as a benign mass or fat necrosis and is known mimic malignancy on ultrasound and mammogram [2, 6]. Some cases may have skin thickening and synchronous or metachronous axillary lymphadenopathy [2].

The final diagnosis is through histopathological evaluation with the hallmark finding of emperipolesis along with S100 immunohistochemical staining that gives a definite diagnosis of Rosai–Dorfman disease. In addition, CD68 immunohistochemical staining confirms the inflammatory nature of the process involving macrophages and monocytes [6, 7]. In our case, the lesion had characteristic accumulation of histiocytes with few displaying emperipolesis with immunohistochemistry showing positivity for S-100 (Fig. 4e) and CD 68.

The disease usually spontaneously resolves and follows a benign course. In few cases, the disease may be progressive with solid organ involvement. These cases carry a bad prognosis especially with the involvement of kidney, liver and lower respiratory tract. In extremely rare cases, Rosai–Dorfman disease can be fatal [2, 8].

Till date no studies could be found to determine the best imaging modality to follow up Rosai–Dorfman disease outside breast. Some studies have shown 18F-fluorodeoxyglucose-positron emission tomography/CT for diagnosis, staging and follow-up [9, 10].

Considering the clinical presentation of a breast lump with skin discoloration and the imaging findings of a superficial, non-circumscribed, highly vascular lesion possibilities of low-grade primary angiosarcoma and hemangioma were considered among the differentials.

Primary angiosarcoma of breast is seen in young females typically in 3rd or 4th decade of life. It presents as a rapidly growing mass with bluish discoloration. Mammography shows non-circumscribed lesions which are heterogeneous on ultrasound with high vascularity on color Doppler. On MRI, they appear T2 hyperintense and T1 hypointense with high-intensity lakes of hemorrhage. Progressive enhancement is seen in low-grade tumors [11].

Breast hemangiomas are superficial subcutaneous or subdermal lesions which appear nonspecific circumscribed oval or lobular on mammography. On ultrasound, large lesions are heterogeneous and highly vascular with serpiginous vessels, often displaying a draining vessel. Limited literature on MRI appearance has shown benign morphological features with avid early enhancement [11, 12].

Conclusion

The present case illustrates that Rosai–Dorfman disease can present as low-grade angiosarcoma clinically as well as on imaging thus a need for high level of suspicion to rule out benign mimics of malignancy to avoid radical surgery is necessary. However, final diagnosis is by histopathology along with immunohistochemical staining. Close surveillance should be maintained as the disease can be progressive and rarely fatal.