Case Presentation – Winter 2017

Colloid Carcinoma

Written by: Theodore Yachimiak, Student, Cleveland Clinic School of Cytotechnology, Cleveland, Ohio

Patient Age: 48-year-old male

Specimen type: FNA of the left breast

Cytologic Diagnosis: Positive

Biopsy : Mucinous, colloid carcinoma. ER positive, PR positive and HER2 negative

Case provided by: This case was provided by Milstead Pathology, Conyers, Georgia

Colloid Carcinoma


Breast cancer in men accounts for less than 1% of all breast cancers.1 The mechanism explaining how male breast cancer occurs is not completely understood, but there are various recognized risk factors, such as occupation risks (high temperature environments or exhaust fumes), hyperestrogenization and radiation exposure.1 Mucinous carcinoma of the breast, also known as colloid carcinoma, is a rare breast malignancy that constitutes around 2% of all breast malignancies. This makes this case especially rare.2,3 This type of breast carcinoma is found more often in women over the age of 60.4,5

Clinical Features:
Tumors of colloid carcinoma of the breast typically present as a palpable lump in the breast.5 They will appear as a well-defined, lobulated lesion by mammography.5 Suspicion for malignancy can depend on the mucin content, with increased mucin content resembling a benign proccess.5

Treatment and Prognosis:
Treatment will depend on a variety of factors, including subtype, stage, hormone receptor status and HER2 status. The ultimate goal is to destroy the tumor cells. This can be accomplished surgically by a lumpectomy or mastectomy followed by radiation or by adjuvant measures, which can include hormonal therapy and chemotherapy.3 Hormonal therapy will target the estrogen and/or progesterone receptors, as colloid carcinomas of the breast are typically estrogen and/or progesterone receptor positive.6 It is generally understood that colloid carcinoma of the breast has a favorable prognosis, with a 10-year survival rate of 80-100%.5,6 The mixed form of colloid carcinoma, which includes infiltrative ductal cells, has a less favorable prognosis than the pure form. The pure form of colloid carcinoma can be described as the tumor being completely surrounded by extracellular mucus. It is thought that the extracellular mucus creates a barrier that can reduce cell invasion, which explains the less aggressive behavior of colloid carcinoma of the breast.5 As with any tumor, the prognosis is always dependent on stage and tumor grade.

The diagnosis of colloid carcinoma of the breast is made by identifying uniform tumor cells floating in a matrix of extracellular mucus. Specimens from colloid carcinoma usually present as small clusters of uniform epithelial cells, but can also present as individual cells. Occasionally, the specimen will have very few cells in a background of abundant mucus.7 The cells can be described as low-grade with mild to moderate nuclear atypia, prominent nucleoli and a moderate amount of cytoplasm.2 Colloid carcinoma also consists of tightly cohesive three-dimensional balls of cells, a prominent mucinous background, cells with vacuolated cytoplasm and plasmacytoid cells.2 Branching capillary structures can also be seen within the pools of mucus.8 It is possible to find bizarrely shaped cells with nuclei appearing of a higher grade.7 Mixed colloid carcinoma tumors will also display a higher grade ductal or lobular component. These tumors are more likely to bleed, which can result in a background of abundant blood and mucus.7

Differential Diagnosis:
There are two lesions most commonly confused with colloid carcinoma of the breast: myxoid fibroadenoma and mucocele.2, 5 Colloid carcinoma can also be mistaken for adenoid cystic carcinoma.4

A mucocele is a pseudocyst, meaning it lacks an epithelial lining. These cysts contain abundant mucin and can occasionally rupture, giving the suspicion of colloid carcinoma.2 Colloid carcinoma can be differentiated from a mucocele by looking for the abundant three-dimensional balls of neoplastic cells seen in colloid carcinoma.

Fibroadenomas are considered the most common benign tumor of the breast found in women.2 Fibroadenomas are hypercellular specimens that appear as large sheets of cells and three-dimensional clusters of cells with an “antler-horn” appearance. They contain bipolar cells, naked nuclei, and stromal fragments and can occasionally present as a myxoid variant. The cells of fibroadenomas have nuclear atypia, dyshesion, maintained nuclear spacing, finely granular chromatin and small, round nucleoli.2 The presence of stripped nuclei, stromal fragments and “antler-horn” arrangements favor a fibroadenoma over a colloid carcinoma, which contains cells with a more clustered three-dimensional pattern.

Adenoid Cystic Carcinoma
Adenoid cystic carcinoma is rarer than colloid carcinoma, with an occurrence rate of less than 0.1%.2 It is cytologically similar to its counterpart in the salivary gland. These tumors are hypercellular and contain nests of cohesive small cells with uniform round or oval nuclei.2 The nuclei are hyperchromatic and have coarsely granular chromatin with a small nucleolus.2 The cells have scant cytoplasm and round globules can be found within cell groupings.2 The lack of a mucinous background and branching capillary structures, as well as increased nuclear atypia favors adenoid cystic carcinoma over colloid carcinoma.


  1. Fentiman IS, Fourquet A and Hortobagyi GN. Male breast cancer. Lancet. 2006; 367(9510):595-604. doi: 10.1016/S0140-6736(06)68226-3.

  2. Cibas ES and Ducatman BS. Cytology: Diagnostic Principles and Correlates. 4th ed. Philadelphia, PA: Elsevier; 2014.

  3. Johns Hopskins Medicine. Mucinous (Colloid) Breast Cancer. Accessed January 24, 2016.

  4. Ali SZ and Parwani AV. Breast Cytopathology. New York, NY: Springer-Verlag New York; 2007.

  5. Tavassoli FA and Devilee P. Pathology and genetics of tumours of the breast and female genital organs. Lyon, France: IARC Press; 2003.

  6. Dumitru A, Procop A, Iliesiu A, et al. Mucinois breast cancer: a Review study of 5 year experience from a hospital-based series of cases. Maedica (Buchar). 2016; 10(1):14-18.

  7. Oertel YC. Fine needle aspiration of the breast. Stoneham, MA: Butterworth; 1987.

  8. Naqos N, Naim A, Jouhadi A, et al. Mucinous carcinoma of the breast: Clinical, biological and evolutive profile. Cancer Radioth. 2016; 20(8):801-804. doi:10.1016/j.canrad.2016.06.008.