Chronic Granulomatous Fungal Disease Masquerading as Breast Cancer in Port Harcourt, Nigeria: A Case Report and Literature Review

<i>Background:</i> Extracutaneous or deep-seated mycosis of the breast tissue is rather rare, however, it has been described in some parts of the world. Available evidence suggested that a decline in reporting might imply neglect or a low index of suspicion. The aim of this study was to report the features of unusual chronic granulomatous fungal disease that presented to our health facility with features of breast cancer in the first half of year 2025. <i>Case Presentation:</i> A 37 year-old breast-feeding mother who presented to General Surgery Outpatient Clinic on referral from a health center with a history of left breast lump of 5 months duration. She had fever at the onset of the illness, associated with breast pain. The swelling had progressed to form multiple “boil” which ruptured and discharged some relatively clear fluid with associated changes in the skin and thickening of the left breast. There were no other remarkable symptoms. She had had antibiotic treatment and a biopsy taken before referral. Significant findings on physical examination included: gross breast asymmetry with the left breast being bigger, showed hyperemic areas, serous discharge, peau de orange with irregularly shaped scar (previous biopsy scar). There was a mass located in the outer upper and inner upper quadrant, measuring 6cm by 8cm with surrounding discharging sinuses. The breast ultrasound scan revealed left-sided complex heterogenous solid mass 5.4cm x 3.5cm with irregular outline; the left axillary lymph node was enlarged and measured 3.2cm x 1.8cm. The tissue histopathology report of Tru Cut biopsy revealed Chronic non-specific/mastitis idiopathic granulomatous mastitis. <i>Conclusion:</i> The symptoms and signs of breast cancer and breast mycosis share some similarities. Breast fungal disease is rare but does occur, and increased awareness is expected for early diagnosis.