Crystallising galactocele of the breast: a rare cytological diagnosis

Abstract

Galactocele of the breast is a benign condition characterised by milk containing cystic lesions, usually present during pregnancy and lactation. The diagnosis of galactocele is difficult due to physiological changes which occur during pregnancy and lactation. Fine needle aspiration cytology proves to be a simple and minimally invasive procedure in diagnosing and treating this condition. Very rarely, long-standing galactoceles can show crystal formation on aspirate smears, termed as crystallising galactocele. Herein, we present this rare case of crystallising galactocele in a 26-year-old lactating woman. We are reporting this case because of its rarity, as less than 10 cases have been reported so far.

Background

Galactocele of the breast is a common benign cystic lesion, usually occurring in pregnant and lactating woman. A galactocele is a retention cyst in the mammary gland and develops due to protein plugging and obstructing lactiferous ducts. Crystallising galactocele is its variant, which is extremely rare and poses diagnostic challenges clinically and radiologically. Fine needle aspiration cytology (FNAC) plays an essential part in resolving this diagnostic dilemma and helping to arrive at a correct diagnosis.

Case presentation

A 26-year-old woman presented with awareness of lump in her left breast in lower inner quadrant for 7 months. She had delivered a male baby 10 months ago vaginally and was lactating since then. There was no history of trauma, serous/bloody discharge from the nipple. Her physical examination revealed a discrete mobile non-tender lump measuring 2×2 cm palpable in the lower inner quadrant of the left breast. Nipple and areola were unremarkable. A clinical diagnosis of fibroadenoma was evoked.

Investigations

On ultrasonography, a well-defined hypoechoic lesion measuring 2.2×2.1 cm was noted and benign aetiology was suggested; however, low risk of malignancy (BI-RADS 4a) was also kept as differential.

Treatment

In view of persistent symptoms, she underwent FNAC of the lesion, which yielded thick white chalky-like material on two different needle passes, and resulted in the reduction of the size of the lesion. The cytology smears were prepared and stained with Giemsa, Papanicolaou and H&E stains. The smears showed numerous angulated crystals of varying sizes in a background of amorphous, granular proteinaceous material. However, no ductal epithelial cells, bipolar nuclei or fibromyxoid stroma were seen. Smears were also seen under polarised microscopy which showed numerous birefringent crystals (figure 1A–D). Hence, a diagnosis of crystallising galactocele of the breast (CGB) was made in view of the crystals seen on smears and the patient’s history of lactation.

Figure 1.

(A) Giemsa-stained cytological smear showing variable-sized crystals (400×); (B) H&E stained smear showing amorphous, granular proteinaceous background (400×); (C) Pap-stained smears showing many angulated crystals in background of amorphous proteinaceous material (400×); (D) crystals show polarisation (100×).

Outcome and follow-up

At 6-month follow-up, she is doing well with no recurrence of symptoms.

Discussion

The galactocele of the breast is a benign cystic lesion, which usually tends to occur during pregnancy and lactation. The predisposing factors include secretory breast epithelium and prolactin stimulation, along with plugging of lactiferous ducts, causing an obstruction.^{1 2} Rarely it can occur in nulliparous women with prolactinaemia, post-menopausal women, in male infants with hyperprolactinaemia, accessory breast tissue in the axilla and after augmentation mammoplasty.³

Galactocele is a cystic collection of milk products that is lined by flattened cuboidal epithelium. They usually present as solitary or multiple painless mobile lumps involving either one or both sides of the breast and usually occur in subareolar region.⁴ Diagnosing galactocele becomes difficult due to specific physiological changes in the breast during pregnancy and lactation, hindering the clinical, radiological and pathological evaluation of a breast lump.⁵

Although most breast lesions during pregnancy and lactation are benign and include galactocele, lactating adenomas or fibroadenoma, they should always be dealt promptly as 3% of breast carcinomas can coincide in this population.⁶ Clinically, the lump gives an impression of fibroadenoma or lactating adenoma; radiologically, galactocele can have a typical appearance if it is anechoic and/or contains fat-liquid level. Depending on its contents, it can resemble an abscess on ultrasound, a solid benign lesion (fibroadenoma, lactating adenoma) or a solid malignant lesion (pregnancy-associated breast cancer). Hence, a pathological diagnosis is always warranted in case of diagnostic doubt.⁴

FNAC is a cost-effective, diagnostic and sometimes therapeutic procedure for the evaluation of palpable breast lumps.⁶ FNAC of galactocele yields thick, chalky white fluid and subsequently reduces the size of the mass. Galactocele is a sterile collection of milk containing variable proportions of mucins (neutral and acid), albumin, lysozyme, lipids and IgA secretory particles.

Crystallisation in galactoceles occurs due to the precipitation of inspissated lactational secretions, mainly fat and proteins.⁴ Cytosmears show amorphous proteinaceous material along with crystals of varying sizes and shapes and are birefringent on polarising microscopy. Crystals demonstrate positivity for periodic acid Schiff and are weakly positive for calcium by the von Kossa technique.¹

CGB has a smooth clinical course and is easily treatable. Mostly, it does not require surgical treatment and usually resolves on its own. Therapeutic aspiration or surgical excision may be required if the lump is painful, enlarged in size or recurs. On reviewing the literature, we have encountered less than 10 such cases, which have been reported so far, and our case added the next one in this category.1 4 6–11

In conclusion, we should keep in mind such rare differential diagnosis of crystallising galactocele when treating cystic breast lesion in pregnant and lactating women. FNAC should always be part of diagnostic armamentarium with clinical judgement to diagnose it.

Learning points.

• Crystallising galactocele of the breast (CGB) should be kept as a differential diagnosis for cystic lesion in lactating breasts.

• Diagnosis of CGB is challenging due to its non-specific symptoms.

• Fine needle aspiration is both diagnostic and therapeutic.

• Larger studies are required to develop more robust data.