tubular carcinoma

Definition: Tubular carcinoma is a special type of breast carcinoma with favorable prognosis, composed of distinct, well-differentiated angular tubular structures (90%+ according to WHO) with open lumina, lined by a single layer of epithelial cells.

Tubular carcinoma shows angular, boat / teardrop shaped infiltrative glands with minimal pleomorphism, with areas of desmoplastic stroma. Tubular carcinoma has a good prognosis relative to invasive ductal carcinoma. It is associated with DCIS and flat epithelial atypia.

Tubular, secretory, medullary, colloid, and adenoid cystic carcinomas have a better prognosis than conventional invasive ductal carcinoma.

Images

 http://webpathology.com/case.asp?case=296

Tubular carcinoma (TCa) is a distinct subtype of invasive ductal carcinoma that is composed of simple neoplastic tubules. It makes up less than 2% of all breast cancers.

The tumor size is less than 2 cm in more than 95% of cases. Most cases are non-palpable and almost always detected on screening mammography. There is a high incidence of multicentricity (56%), bilaterality (38%) and family history (40%) associated with TCa.

Microscopy

The glands of tubular carcinoma are “boat” or “comma” shaped with a single lining of malignant cells with low pleomorphism, in a background of fibroplasia.

Tubular carcinoma tend to be stellate or irregular lesions with infiltrating borders. There is an irregular proliferation of small glands and tubules lined by a single layer of cuboidal or columnar epithelium. At least 90% or more of the lesion should have this architecture to be classified as tubular carcinoma. The glands and tubules have angulated contours and widely open lumens. The neoplastic epithelium is homogenous and lacks significant atypia. Perineural invasion and lymphovascular invasion is rarely seen. The tubules are separated by abundant stroma containing myofibroblasts, elastic tissue, and myxoid matrix.

Microcalcifications are present in about 50% of cases. Low-grade DCIS (micropapillary and cribriform type) as well as columnar cell hyperplasia with atypia (flat epithelial atypia) are considered to be the precursor lesions and are found in two-thirds of cases of TCa. ER and PR are usually positive whereas HER2/neu is negative.

More than 90% of women with TCa present at Stage I. The frequency of axillary lymph node metastases is about 10%. The metastatic deposits sometimes mimic benign glandular inclusions such as endosalpingosis. The treatment usually consists of breast-conserving surgery followed by adjuvant radiation therapy. When the diagnostic criteria are applied strictly to tumors consisting entirely or almost entirely of tubular elements, the prognosis is excellent.

Not actually tubular, this tubular pattern is better described as a necklace formed by a string of beads.

Differential diagnosis

 mammary small glandular proliferations

• mammary tubular carcinoma (MTC)
• sclerosing adenosis (http://www.webpathology.com/image.asp?n=11&Case;=296)
• microglandular adenosis (MGA) (http://www.webpathology.com/image.asp?n=10&Case;=296)
• radial scar
• low-grade adenosquamous carcinoma (LGASC)
• displaced epithelium
• syringomatous adenoma

 http://www.webpathology.com/image.asp?n=9&Case;=296
 http://www.webpathology.com/image.asp?n=11&Case;=296
 http://www.webpathology.com/image.asp?n=10&Case;=296