Adenoid cystic carcinoma

Term

Three years after the first description of the tumor entity by Robin and Laboulbene the surgeon Theodor Billroth in 1856 coined the term first Cylindroma, alluding to the histologically recognizable, cylindrical, lined by tumor cells Bindegewebsformationen within the tumor tissue. Be distinguished from today is the dermal cylindroma, a benign tumor of the skin appendages. The term adenoid cystic carcinoma was first used by the pathologist James Ewing and refers to the typical histological appearance of the tumor, the glandular ( adenoid ) and some wide, of epithelium -lined (cystic ) or not epithelial -lined ( pseudocystic ) cavities formed. Commonly used was the term with the inclusion in the WHO classification in 1972 after a proposal by Thackray and sorbic.

Epidemiology

The peak age of the disease lies in the 4th - 6th Decade of life, where the tumor rarely can already occur in childhood. Women are slightly more often affected than men (3: 2).

Etiology

The tumor formation underlying causes are unknown. Likewise, there are no findings on genetic or environmental risk factors that favor the development of disease. At the molecular genetic level, inactivation of the p53 tumor suppressor gene has been demonstrated in advanced and aggressive forms of adenoid cystic carcinoma. In a recent study, the deletion of the chromosomal region 1p32 - p36 was identified as the most common genetic abnormality in the adenoid cystic carcinoma.

Pathology

Adenoid cystic carcinomas appear macroscopically as a solid, well-circumscribed, but unencapsulated tumors from light brownish color and of variable size. Histologically, the tumor itself is composed of ductal and myoepithelial cells modified, the tubular, forming cribriform and solid growth pattern. The tumor grows constantly infiltrating into the surrounding tissue and spreads in particular along nerve structures ( perineural invasion ).

Diagnosis

A definitive diagnosis is made only after removal of tumor tissue (biopsy, fine needle aspiration ) and microscopic examination by a pathologist. In the propagation of diagnostic imaging processes such as computed tomography, magnetic resonance imaging or positron emission tomography for the application.

Differential Diagnosis

The main entities that need to be distinguished from adenoid cystic carcinoma are pleomorphic adenoma, polymorphous low-grade adenocarcinoma of the, the basal cell adenoma or adenocarcinoma and basaloid squamous this.

Therapy

Basis of therapy is typically the fullest possible surgical removal of the tumor with a sufficient safety margin. Postoperative radiotherapy can reduce the relapse rate and is therefore recommended in some studies as a standard therapy. An effective chemotherapy of adenoid cystic carcinoma is not yet available. Combination therapies of radiation and chemotherapy are currently being tested.

Forecast

The slow but inexorable progression of frequently adenoid cystic carcinoma is reflected in the survival rates. The 5- year survival rate is 89% initially relatively low, but falls after 10 years at 65 % and after 15 years at 40 %. Prognostically significant factors are the histological growth pattern, the tumor location, tumor size, tumor stage, a bone infection and the status of surgical resection margins. Tumors with a tubular or cribriform growth patterns often show a more favorable clinical course than tumors have histological about 30 % solid Gewebsmuster. A lymph node involvement is relatively uncommon with a relative frequency of 5 to 25%. Distant metastases, affecting in descending order of frequency lung, bone, brain and liver, occur in 25-55 % of cases; only about 20% of affected patients survive 5 years.