An unusual cause of hematuria: Primary bladder melanoma in an old man

Emanuela Altobelli1, Rocco Papalia1, Alessandro Giacobbe2, Devis Collura2, Cristina Falavolti1, Ervin Shehu1, Elia Luperto1, Marisa Kurti1, Riccardo Mastroianni1, Giovanni Muto1
  • 1 Università Campus Bio-Medico (Roma)
  • 2 Ospedale San Giovanni Bosco (Roma)

Objective

Primary malignant melanoma of the bladder is a very rare event; most commonly, malignant melanomas of the bladder are metastatic lesions. 26 cases of primary melanoma of the bladder have been reported.
We report a case of primary bladder melanoma without involvement of other sites.

Materials and Methods

In January 2015, an 81-year-old man was admitted to our Geriatrics Unit for an episode of gross hematuria in the previous month, in the absence of any symptoms. The medical history included hypertension, hypothyroidism treated with L-thyroxine, peripheral arterial disease, and corneal transplantation at the age of 74. Urine cytology identified atypical cells, but analysis was not diriment. The patient underwent cystoscopy, with evidence of three esophytic lesions on which multiple biopsies were performed. Histology revealed groups of neoplastic cells with focal intracytoplasmatic melanin pigmentation. Immunohistochemistry revealed positivity for HMB45, MART-1, and S-100. Thus, a diagnosis of bladder melanoma was made.
At a further cutaneous examination, two nevi were detected and surgically removed; both were dysplastic without any sign of melanoma. A PET-CT did not reveal any further neoplastic localization. A gastrointestinal endoscopy was as well negative. An ophthalmic exam with fundus oculi exam did not evidence retinal melanoma.

Results

The patient underwent total cystoprostatectomy with ureteroileal anastomosis.
Anatomic and histological examination showed two ulcerated lesions (2,5 cm and cm 1 in diameter respectively), involving the posterior wall. The lesions were totally sampled embedded in paraffin and were cut at 3 μm thickness for standard histology and for immunohistochemical studies.
The lesions showed a proliferation of epithelioid-like cells, characterized by ample eosinophilic cytoplasm, nuclear irregularity and pleomorphism, with conspicuous nucleolus, and arranged in solid nests. The neoplasia involved the mucosa, muscular and adipose tissue of bladder’s wall.
Pigment deposits were also present in the neoplastic tissue. Immunohistochemistry was performed by the streptavidinbiotin method. The antibodies used were mouse monoclonal antibodies against HMB-45, MART-1 and S100 protein, all from Dakocytomation, Denmark. Sections were incubated with LSAB2 (Dakocytomation). 3-3-Diaminobenzidine (DAB) was used for colour development and haematoxylin was used for counterstaining.
Immunohistochemical analysis evidenced positivity of neoplastic cells for HMB45, MART1 and, focally for S100 protein. These findings confirmed the diagnosis of malignant melanoma. Also, a prostate cancer with a Gleason score of 7 (4+3) was diagnosed.
During the postoperative course, the patient experienced wound dehiscence, sepsis, and respiratory insufficiency. In agreement with the patient and family, because of the patient’s age, and comorbidity, no further therapies were performed.
After 12 months, the patient is still alive and independent in the basic activities of daily living, apparently disease free. Furthermore, the PSA is <0.01 ng/mL.

Discussions

Primary malignant melanoma is uncommon in the genitourinary tract, especially in the bladder. According to literature, age at presentation of primary bladder melanoma ranges between 7 and 91 years (59 ± 17).
The origin of malignant melanoma in the bladder is still unclear. According to the ectopic theory, melanocytes would migrate from the neural crest through the mesenchyme toward the skin and hair follicles, possibly stopping in ectopic locations, including a developing bladder. Another hypothesis is that argyrophil urothelial cells are derived from urothelial stem cells with differentiation in the direction of neoplastic melanocytes.
In the absence of a clinical history of melanoma, other lesions with an infiltrative growth pattern and similar cytomorphology may be considered. The possible list of differential diagnoses includes high grade urothelial carcinoma, prostatic carcinoma in male, Mullerian carcinomas in female, lung carcinoma, breast carcinoma, and rare entities like paraganglioma and sarcomatoid carcinoma.

Conclusion

There is no consensus opinion regarding the best treatment option in the management of primary malignant melanoma of the urinary bladder, due to the paucity of cases so far reported. To date, the prognosis of primitive malignant melanoma is still poor. Trials involving treatment options aimed at improving patient's survival and quality of life are urgent. In this perspective, our case report seems of special interest because our patient, though being frail and multimorbid, successfully underwent major surgery and is free from release and in good clinical status after one year. In conclusion, this case report shows that bladder melanoma, though distinctly rare, should be suspected at any age and might be amenable to a radical treatment even in very old and frail patients

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