Cytodiagnosis of herpes simplex mastitis: Report of a rare case.

Herpes simplex virus (HSV) is a rare cause of breast infection. Few cases of maternal-infant transmission of the virus during breastfeeding resulting in nipple lesions have been documented. Only three cases have been reported in nonlactating women. We report an additional case of HSV mastitis in a 36-year-old nonlactating female who was diagnosed on scrape cytology smears.

Introduction

Herpes simplex virus (HSV) mastitis in a nonlactating female is extremely rare. To the best of our knowledge, only three cases have been reported so far.[1] We describe the first case of herpes simplex mastitis diagnosed on scrape cytology smears prepared from the ulcer over the nipple of the left breast. Possible modes of infection and the importance of distinguishing these cases from other causes of mastitis are also discussed.

Case Report

A 36-year-old lady presented to the outpatient department with pain and swelling in the left breast since two days. She had been given oral ciprofloxacillin and topical mupirocin by the local physician, but there was no improvement in her condition. The patient denied history of recent breast trauma or previous breast lesions. On examination, there was 10 cm area of indurated erythema on the medial aspect of the left breast along with an ulcer measuring five mm in diameter on the medial aspect of the nipple. Air-dried smears prepared from the scrapings of the ulcer were sent to us for cytological examination.

Microscopic examination of scrape cytology smears revealed isolated as well as aggregates of keratinocytes showing marked nuclear pleomorphism and nuclear enlargement. These keratinocytes revealed homogenous opaque nucleus and dense basophilic cytoplasm with well-defined cell boundaries [Figure 1]. Numerous multinucleated giant cells with ground glass nucleus and nuclear molding were also seen [Figure 1].

Figure 1

Keratinocytes showing marked nuclear pleomorphism and nuclear enlargement (Giemsa, ×200); inset shows multinucleated giant cells with ground-glass nucleus and nuclear molding (Giemsa, ×400)

Discussion

The most common sites of HSV infection are around the oral cavity and genitalia. However, herpes simplex can affect any skin or mucous membrane surface, in addition to the eyes, central nervous system and viscera. One rare site of HSV infection of the skin is the breast.[12] Only 2% of all extragenital herpetic lesions have involved the breast.[3]

Few cases of maternal–infant transmission of the virus during breastfeeding resulting in nipple lesions have been documented[4-6] and only rare cases have been reported in nonlactating women.[1] Furthermore, development of breast lesions as the first and the sole manifestation of clinically apparent HSV infection without oral or genital herpes is uncommon.[7] There is little information regarding transmission of HSV to the breast except in cases associated with neonatal breast feeding.

In the present case, further enquiry failed to reveal the source of HSV infection and we are left to speculate the mode of infection. There can be two possible modes. The first possibility is that the virus was transmitted to the breast through autoinoculation from an asymptomatic oral or genital lesion. Autoinoculation to other body sites such as face, fingers and eyes has been documented.[37] But, there are only two cases documenting such an autoinoculation to the breast.[18] The second possibility is that the present lesion may be a primary infection of the breast from recent sexual contact with an asymptomatic HSV carrier. The infected asymptomatic carrier can carry the virus in the saliva and can transmit the virus through close personal contact.[79]

Kobayashi et al.[10] have described the cytologic changes in the smears from nipple discharge of two cases with HSV infections. The cytology of nipple discharge smears of their cases revealed the ground-glass appearance of the nuclei with multinucleated syncytial cells. In addition, positive hybridization was found with intense staining for the HSV DNA in the nuclei of cells having a ground-glass appearance. They concluded that cytologic observation together with an in situ hybridization procedure may be a rapid and valuable tool for the detection and final demonstration of HSV infections.

In contrast to impression cytology, the scrape cytology is a traumatic procedure. Scraping the lesion collects in situ cells. It samples a much smaller area restricted to the lesion. It is more prone to the air-drying artifacts. A certain degree of expertise is required for scraping and making the smear. In scrape cytology smear, cell-to-cell relation is not maintained. To compensate for all these drawbacks, scrape cytology offers a better cell yield even in keratinising lesions and small focal lesions. Results of scrape cytology are likely to be more specific and sensitive. In our case, air-dried scrape cytology smears stained with Giemsa stain revealed characteristic cytological features of HSV infection.

It is important to establish the correct clinical diagnosis and confirm it with cytology smears. HSV infection should be considered in any case of ulcerating mastitis unresponsive to antibiotics. It is also important to distinguish herpes mastitis from bacterial mastitis since herpes mastitis heals spontaneously in 7–10 days without scarring, whereas bacterial abscess requires surgical drainage with residual scarring. In addition, it is important to distinguish herpes simplex mastitis from varicella zoster mastitis, because zoster infection can become confluent, hemorrhagic, heal slowly with scarring and can be associated with residual neuralgia.

To conclude, in suspected cases, scrape smears can be of great value in the early diagnosis of herpes simplex mastitis.