Extensive Presentation of Penile Carcinoma Cuniculatum a Variant of Squamous Cell Carcinoma With Low Malignant Potential.

Carcinoma cuniculatum is an uncommon variation of squamous cell carcinoma (SCC) has been documented in a few cases at various locations of the body such as penis, foot, jaw, oropharynx and esophagus. In this case, a 79-year-old male presents with a penile mass, which he underwent a total penectomy. Histology of the mass was defined as carcinoma cuniculatum with negative margins and no lymphovascular invasion. This variant of SCC rarely metastasizes. A joint decision was made to observe lymph nodes. It is important to differentiate the different SCC because patient care can be guided based on the pathology.

Introduction

Penile carcinoma is a very rare cancer in industrialized countries. The prevalence of circumcisions in childhood is a major factor for decreasing the risk of invasive penile cancer. Less than 1% of all tumors in males are penile carcinoma. In this group, 95% of penile carcinoma is classified under squamous cell carcinoma (SCC). Risk factors for SCC are smoking, human papillomavirus (HPV) infection, phimosis, lichen sclerosis, poor hygiene. There are many variants of SCC which include, the usual type which is the most common variant, verrucous, warty, papillary not otherwise specified (NOS), basaloid, sarcomatoid, cuniculatum, pseudohyperplastic, adenosquamous and pseudogldandular.

One exceeding rare type of SCC is carcinoma cuniculatum which accounts for less than 1% of penile carcinoma. Only 8 cases of penile carcinoma cuniculatum have been reported in the literature. Initially, the lesion resembles a wart but it progresses to large exophytic tumor which eventually becomes ulcerated developing numerous sinuses from which a foul smelling keratinous exudate. Grossly indistinguishable from other verruciforms however microscopically cuniculatum has unsusal sinus like endophytic burrowing growth pattern. Cuniculatum pattern first described in 1954 by Ayrd which was a description of a plantar skin lesion. This neoplasm has been described in many other sites of the body such as oral cavity and pharynx, esophagus, jaw, sacrum, nasal cavity, oral cavity, buttocks, hands, toes, thumb, abdominal wall, and intertriginous areas. There have been no metastatic cases of penile carcinoma cuniculatum. However, one metastatic case was documented from a 12-year long standing carcinoma cuniculatum which was resected and recurred with delayed presentation on the sole of the foot which metastasized to the skin and lymph nodes. This case report presents an extensive carcinoma cuniculatum involvement of the entire length of the penis, managed without immediate lymph node dissection.

Case report

A 79-year-old male presents to his primary care physician (PCP) for routine follow up. The patient's wife noticed that her husband was putting toilet paper in his underwear to prevent drainage and blood from messing up his underwear. She encourages the PCP to exam the patient. It was noted on exam, indurated phallic mass with ulcerations and drainage from the sides, extending the length of the penis from the meatus to the base. It was reported it took patient 20 min to urinate. Patient was treated for cellulitis which did not resolve and subsequently referred to urology. He was evaluated and worked up for penile cancer. No palpapable lymph nodes on physical exam or lymphadenopathy on CT scan. Patient was insisting to have a penectomy performed as early as possible. He underwent a total penectomy with perineal urethrostomy without lymphadenectomy (Fig. 1).

Figure 1

a. Anterior view of the penis meatus. b. Side view of the penis with sutures attaching at the base of the penis. c. Perineal urethrostomy with urethral catheter.

On histopathology of penis specimen was invasive moderate to well differentiate squamous cell carcinoma with features of carcinoma cuniculatum type. The tumor involved the entire glands extending into the squamous mucosa prepuce to corpora spongiosum. One margin was close to the tumor but free of carcinoma. It was characterized as verroucous (condylomatous) growth and serpiginous sinus tracts with pushing boarders, which is consistent with carcinoma cuniculatum. No lymphovascular margins were involved with pathological staging as pT2 (Fig. 2).

Figure 2

Low power image of squamous cell carcinoma, carcinoma cuniculatum type, is considered a low grade tumor characterized by verrucous (condylomatous) growth and serpiginous sinus tracts with pushing borders.

Discussion

The case is unique because it is the only description of carcinoma cuniculatum extending throughout the penis. The pathology is considered low grade with low malignant potential to spread. There was no lymphovascular invasion identified. Despite the pathological diagnosis of the cancer of pT2, a lymph node dissection was not preformed. Previous reports were not as locally extensive however no metastases to lymph nodes or extra-nodal occurred from the penis. This was a joint decision between the patient and physician to surveil lymph nodes through clinical exam and imaging with possible delayed lymphadenectomy. Because of the unique variant of this penile cancer it was decided that observation was a reasonable option for this patient.

Conflict of interest

There was no conflict of interest in the management of the patient's penile cancer.