Carcinoma Cuniculatum: A Distinctive Variant of Penile Squamous Cell Carcinoma

Abstract

We are reporting a peculiar variant of penile squamous cell carcinoma (SCC) characterized by its peculiar deeply penetrating and burrowing pattern of growth. This low grade, verruciform penile neoplasm is similar to the plantar epithelioma cuniculatum originally described by Ayrd in 1954. Clinical and pathologic features of 7 patients are presented. There were 7 partial penectomies and 4 bilateral inguinal node dissections. The mean patient's age was 77 years. Grossly, the tumors were white to gray, exo-endophytic, and papillomatous with a cobblestone or spiky appearance. All cases affected the glans and extended to coronal sulcus and foreskin (average size was 6.3 cm). The hallmark of the lesion was noted on cut surface where there were deep tumoral invaginations forming irregular, narrow, and elongated neoplastic sinus tracts connecting the surface of the neoplasm to deep anatomic structures. The neoplasm invaded through lamina propria and corpus spongiosum and grew along the loose connective tissue of Buck fascia to involve the tunica albuginea and corpora cavernosa (average depth was 32 mm). Deeply invasive keratin filled cysts or crypts, on serial sections, showed to be connected to the surface tumor. Fistulization to the skin was also noted. Microscopically, the lesions corresponded to well-differentiated carcinomas with bulbous front of invasion. There were focal areas of higher histologic grade and more infiltrative and jagged borders in 4 cases. Inguinal nodes were negative in 4 patients in which groin dissection was performed. Carcinoma cuniculatum is a variant of penile SCC with distinctive growth pattern and should be distinguished from other verruciform tumors such as the verrucous, papillary, and warty carcinomas. Unlike most subtypes of penile SCCs and despite the deep invasion, none of the tumors showed groin or systemic dissemination at time of diagnosis.

Carcinoma Cuniculatum of the Esophagus and Tongue: Report of Two Cases, Including TP53 Mutational Analysis

“…CC most often occurs in the skin, but have also been described in other sites, including esophagus [2,3], oral cavity [4,5], gingiva [6], tongue [7], penis [8], larynx [9] and nail [10]. In its pure form this neoplasm has only capacity for local infiltrative growth, but not metastasis [3,8].…”

“…A solely endophytic CC may have an inverted papilloma-like appearance but deep tissue penetration is not seen in the latter. In tumors with a mixed exo-endophytic growth pattern, other verruciform tumors such as classic verrucous carcinoma, mixed verrucous-conventional squamous cell (hybrid) carcinoma, well differentiated squamous cell carcinoma with verrucous features and warty (condylomatous) carcinoma should be considered (see below) [2,8].…”

“…Warty carcinoma differs from VC in that it displays, in addition to a verrucous/warty architecture, high-grade cytologic atypia and viral (HPV) cytopathic effect [8]. A particularly challenging differential diagnostic possibility for purely endophytic CCs of the esophagus is esophageal pseudodiverticulosis (EPD) [3].…”

“…The very well differentiated light microscopic features of this tumor led the authors to label it as ''epithelioma cuniculatum''. The most commonly involved site for CC is the skin with a predilection for the sole, but noncutaneous sites, such as esophagus [2,3], oral cavity [4,5], gingiva [6], tongue [7], penis [8], larynx [9] and nail [10] are also on record. CC is histologically typified by deeply invaginating, keratin filled, sinus-like structures which have been likened to rabbit burrows (lat.…”

“…There may or may not be an associated exophytic component [2]. The former has led many investigators to view CC and verrucous carcinoma (VC) as two ends of a spectrum of extremely well differentiated SCC, which when pure, only have the capability for local infiltration and lacks metastatic potential [3,8]. Herein, we present the clinicopathological features of two cases of CC; one lingual and one esophageal case with a molecular genetic study regarding the mutational status of the TP53 gene of the esophageal case.…”