Crystallizing Galactocele – A Rare Variant Diagnosed on Fine Needle Aspiration Cytology

Dear Editor, Galactocele is a benign breast retention cyst that occurs almost exclusively in lactating females. Crystallizing galactocele is a rare variant that develops when the cyst contents crystallize. It poses a diagnostic challenge both clinically and radiologically.[1,2] A female patient aged 43 years presented in the fine-needle aspiration (FNA) clinic with a history of swelling in her right breast for the past year. She had a history of childbirth 2 years back and had breastfed for 1 year. She noticed a lump in the breast around 1 year postpartum. A 1 cm × 0.5 cm lump was noted in the right breast in the upper inner quadrant on breast palpation. It was mobile, nontender, and firm to feel. On ultrasonography, a well-defined heterogeneously hypoechoic area of size 1.2 cm × 0.3 cm was noted at a 3’o-clock position in the right breast at the nipple-areola complex, and benign etiology was suggested (BIRADS II). Nipple and areola complex was unremarkable. FNA cytology (FNAC) was performed under aseptic precautions. The aspirate was thick and chalky white that obstructed the needle. There was a mild reduction in swelling after aspiration. The smears were prepared and stained with hematoxylin and eosin stain in addition to the May-Grunwald Giemsa stain. The smears depicted many refractile crystals of variable shape and size with defined borders [Figure 1a and b]. Tyrosine-like crystals were also noted. These crystals showed birefringence under a polarizing microscope [Figure 1c]. There was proteinaceous and amorphous material in the background. Clusters of benign ductal epithelial cells were seen along with foamy macrophages and foreign-body giant cells.Figure 1: (a and b) Smears show many refractile crystals of variable shape and size with defined borders. (a) MGG, ×200; (b) H and E, ×200; (c) Crystals depicting birefringence under a polarizing microscope. MGG, ×200. MGG: May-Grünwald giemsaGalactocele is a cystic structure lined by a flattened cuboidal epithelium containing milk products. It usually tends to occur during pregnancy and lactation.[1,3,4] The factors that influence cyst formation include plugging of lactiferous ducts, prolactin stimulation, and secretory type of breast epithelium.[2,3,5] Milk contains carbohydrates, minerals, and a variety of proteins aggregate. Precipitation of inspissated milk secretion, especially fats and proteins results in crystallization. As a result of the acidic climate, these milk substances’ supersaturation prompts the arrangement of tyrosine or calcium lactate stones. These crystals are typically made from potassium, calcium, sulfur, and chlorine.[1,6] In 1997, the first case of crystallizing galactocele was described by Raso et al. They concluded that a diagnosis of crystallizing galactocele should be contemplated when FNA from a breast lump in a pregnant or breastfeeding female yields milky, viscous fluid.[2] Few cases of crystallizing galactocele have been described previously on FNAC. These cases also presented multiple dark blue/purple refractile crystals of variable shapes and sizes.[2,3,5-9] Most were positive for birefringence under polarizing microscopy like in our case.[1-4,7,9] Shetty et al. reported tyrosine-like crystals which were also seen in the present case.[4] Radiologically, these lesions are difficult to differentiate from benign breast abscesses or carcinomas as few carcinomas enlarge during pregnancy under the influence of hormones. Clinically, the differential diagnosis includes fibroadenoma, lactating adenoma, and traumatic fat necrosis.[1,2,10] Calcium phosphate and calcium oxalate crystals are associated with malignant and benign breast lesions. Extremely low cellularity with prominent refractile, polarizable, birefringent, crystals, and cells exhibiting lactational changes favors the diagnosis of galactocele. Galactocele usually resolves without any treatment or surgical intervention. FNAC helps to clinch the diagnosis and also has therapeutic benefits.[2] In conclusion, crystallizing galactocele is a very rare breast lesion seen in pregnant or lactating females which can sometimes be a diagnostic challenge clinically as well as radiologically. A chalky fluid aspirate with microscopic examination depicting numerous refractile crystals of variable shape and size in a background of amorphous and proteinaceous material points toward the diagnosis of crystallizing galactocele. Thus, FNAC helps in the accurate diagnosis of crystallizing galactocele. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.