Basal Cell and Adenoid Cystic Carcinoma

Rafael E. Jimenez, MD

Gladell P. Paner, MD

Mahul B. Amin, MD

Key Facts

Terminology

Malignant neoplasm composed primarily of basaloid cells arising putatively from prostatic basal cells

Clinical Issues

Wide age range (28-89 years), but majority occur in older men
Most commonly presents with obstructive urinary symptoms
Normal serum PSA level
Local recurrence, metastasis, and death from disease reported in approximately 30% of cases

Macroscopic Features

White and fleshy tumor with ill-defined infiltrative edges and may have microcystic features
Tumor primarily centered in transition zone, with variable peripheral zone involvement

Microscopic Pathology

Basaloid tumor cells have scant cytoplasm, high nuclear to cytoplasmic ratio, and irregular or angulated nuclei with open chromatin
Infiltration of adjacent parenchyma is hallmark feature for diagnosis of malignancy
2 main histologic patterns
- BCC consisting of variably sized solid nests, cords, or trabeculae with peripheral palisading of cells
- ACC consisting of infiltrative nests with prominent cribriform architecture

Ancillary Tests

Basal cell markers(+) and usually PSA/PSAP(-)

BCC/ACC may present with 2 patterns. The BCC pattern is characterized by infiltrative solid nests of basaloid cells with peripheral cellular palisading, similar in appearance to cutaneous BCC.

The ACC pattern is characterized by large, invasive nests with cribriform architecture containing multiple lumina resembling ACC at other sites. BCC and ACC patterns may coexist in the same tumor.

TERMINOLOGY

Abbreviations

Adenoid cystic carcinoma (ACC)
Basaloid cell carcinoma (BCC)

Synonyms

Adenoid basal cell tumor, adenoid cystic-like tumor

Definitions

Malignant neoplasm composed primarily of basaloid cells arising putatively from prostatic basal cells

ETIOLOGY/PATHOGENESIS

Origin

Considered to arise from basal cells along prostatic ducts and acini

CLINICAL ISSUES

Epidemiology

Incidence
- Uncommon: Approximately < 75 cases reported in the literature
Age
- Wide age range (28-89 years), but majority occur in older men

Presentation

Most commonly presents with obstructive urinary symptoms
- Thus most cases diagnosed on transurethral resection of prostate (TURP) specimens
Perianal pain
Few tumors incidentally encountered in needle biopsy during work-up for elevated serum PSA level for other causes

Laboratory Tests

Serum PSA levels may be normal or elevated

Treatment

Most reported cases treated with TURP, with a subset undergoing radical prostatectomy
Advanced stage treated with adjuvant radiotherapy or chemotherapy

Prognosis

Limited data available on clinical behavior
Local recurrence, metastasis, and death from disease reported in approximately 30% of cases
Metastases commonly to lung and liver
Bone metastasis rare compared to acinar adenocarcinoma
Presence of large solid nests with central necrosis, high Ki-67 staining, and less immunoreactivity to basal cell markers suggested to be associated with aggressive behavior

MACROSCOPIC FEATURES

General Features

Grossly apparent tumor that is white and fleshy with ill-defined infiltrative edges
May have microcystic features

Site of Involvement

Tumor widely involving prostate, including peripheral zone

MICROSCOPIC PATHOLOGY

Histologic Features

Basaloid tumor cells have scant cytoplasm, high nuclear to cytoplasmic ratio, and irregular or angulated nuclei with open chromatin
Basaloid cells may exhibit nuclear and cytoplasmic microvacuolation
Infiltration of adjacent parenchyma is hallmark feature of BCC
BCC pattern
- Variably sized solid nests, cords, or trabeculae with peripheral palisading of basaloid cells
- May be associated with extensive central necrosis
ACC pattern
- Tumor grows in nests with prominent cribriform architecture
- Eosinophilic, hyaline, basement membrane-like material may be present
- Basophilic mucinous secretions may be present in lumina
Additionally, tubuloglandular pattern with collagenous rim and basal cell hyperplasia-like patterns may occur
Combination of these different architectural patterns is often encountered
Usually associated with desmoplastic stromal response, which may be fibromyxoid or myxoid
Rarely acinar, sebaceous, or squamous cell differentiation may be present
Perineural invasion, angiolymphatic invasion, or necrosis may be present
Extraprostatic extension is often present, including involvement of bladder neck or seminal vesicle
Tumor involvement of thick bladder neck muscles detected with relatively high frequency in TURP specimens
Subset may have synchronous or metachronous prostate cancer, such as acinar adenocarcinoma, sarcomatoid carcinoma, or small cell carcinoma