Penis and scrotum - Basaloid carcinoma

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Penis and scrotum

Squamous cell carcinoma and variants

Basaloid carcinoma

Editors: Antonio Cubilla, M.D. and Alcides Chaux, M.D. (see Authors page)

Revised: 5 May 2010, last major update April 2010

Definition

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● Squamous cell carcinoma composed of uniform, small to intermediate cells in solid sheets or nests, often with central comedo-like necrosis

● ICD-0: 8083/3

Epidemiology

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● 4-10% of all penile carcinomas (Anal Quant Cytol Histol 2007;29:185)

● Median age 52 years (range 33-84 years)

Sites

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● Glans is the preferred site but extension to coronal sulcus and inner foreskin is common

Etiology

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● HPV detected in 71-81% of all cases (HPV-16 in 81% of all positive tumors, Am J Pathol 2001;159:1211)

Clinical behavior

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● Aggressive, high-grade, deeply invasive penile tumor

● Inguinal nodal metastases in 50-100% (J Urol 2006;176:1431) and local recurrence in 36%

● High mortality rate (21-67%)

Prognostic factors

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● Regional metastasis and mortality associated with tumor thickness > 10 mm and infiltration of corpus cavernosum (Am J Surg Pathol 1998;22:755)

Treatment

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● May require total penectomy, bilateral groin dissection and adjuvant chemotherapy from the onset (Am J Surg Pathol 2009;33:1299)

Gross description (Macroscopy)

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● Flat, ulcerated, irregular mass, with solid tan tissue replacing corpus spongiosum and invading tunica albuginea and corpus cavernosa

● Mean tumor size of 3-4.5 cm

Gross images

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Top: Distal penis is extensively involved by yellow-white tumor with typical vertical growth pattern of this variant; also involvement of mucosal aspect of foreskin and glans, corpus spongiosum, corpus cavernosum, tunica albuginea and urethra

Bottom: Diagram shows tumor in yellow with focal necrosis (n) and other landmarks (cos: coronal sulcus, cc: corpus cavernosum, ab: tunica albuginea, u: urethra, mr: margin of resection)

Other images: #1

Micro description (Histopathology)

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● Closely attached nests of tumor cells, often with central comedo-like necrosis

● Vertical growth pattern is typical

● Composed of small-to-intermediate basophilic cells with scant cytoplasm, indistinctive cell borders, and high mitotic/apoptotic rate

● Occasionally peripheral palisading and focal central abrupt keratinization

● May have peripheral clefts due to retraction artifact

● Frequently associated with basaloid or warty penile intraepithelial neoplasia (Int J Surg Pathol 2004;12:351)

● Prominent perineural and vascular invasion

Micro images

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Closely packed nests with focal central Basaloid features on higher power,

comedonecrosis infiltrating deeply into with starry sky appearance

the corpus spongiosum of glans

Focal necrosis Small cells with hyperchromatic nuclei

and mitotic activity are typical features

Figure 1C

Contributed by Dr. Alcides Chaux and Dr. Antonio Cubilla:

Tumor nests composed of a uniform population of small to medium-sized neoplastic cells with scant cytoplasm, indistinct cell borders, high mitotic/apoptotic rate, abrupt parakeratosis, and central (comedo-like) necrosis

In spite of the presence of pleomorphic cells (upper field), this tumor maintains all the features of basaloid carcinoma with a nesting pattern of growth, indistinct cell boundaries, abrupt keratinization, and central comedonecrosis

Basaloid carcinoma showing an exophytic papillary pattern of growth with papillae lined by neoplastic cells depicting all the features of basaloid differentiation (uniform population, scant and basophilic cytoplasm, indistinct cell borders and high mitotic/apoptotic rate)

Positive stains

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● Cytokeratin 34bE12

● Also p16INK4a, topoisomerase II alpha (BJU Int 2008;102:1040)

Differential Diagnosis

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● Basal cell carcinoma: neoplastic cells have less atypia, tumor occurs usually in skin of shaft, nests have prominent peripheral palisading, characteristic myxoid stromal changes

● Neuroendocrine carcinoma: similar morphology; immunohistochemistry for neuroendocrine differentiation may be useful

● Poorly differentiated usual squamous cell carcinoma: more irregular nests, neoplastic cells with eosinophilic cytoplasm and distinct cellular boundaries, gradual (not abrupt) keratinization and clear tendency towards squamous differentiation

● Urothelial carcinoma: more pleomorphism, features of urothelial differentiation usually evident in the invasive or in situ component, positive for uroplakin-III and thrombomodulin

End of Penis and scrotum > Squamous cell carcinoma and variants > Basaloid carcinoma

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