CASE OF THE WEEK
Editors: Francesca Khani (Frk9007@med.cornell.edu) and Mahmut Akgul (akgulm@amc.edu)
2022-07/February 14
Contributors: Alessia Cimadamore, Rodolfo Montironi
During follow-up for urothelial carcinoma of the upper urinary tract, aman, aged79years,underwent a cystoscopy andincidentally discovered anexophytic blueish areaon the bladder dome, covered by flat and smooth urothelium.The urologist performed an en-bloc resectionof the lesion.
Quiz
1. What is the correct diagnosis?
a) Inflammatory fibrous reaction withhemosiderin deposition
b) Melanoma of the bladder
c) Blue nevus of the bladder
d) Pigmented schwannoma
e) Sarcomatoid carcinoma with melanocytic differentiation
1. c
Blue nevus of the urinary bladder
Common blue nevus generally occurs on the skin, with predilection to the dorsal aspect of the hands and feet, buttocks, scalp and face. Rare examples have been reported in extracutaneus sites, including oral mucosae, vagina, cervix, prostate, spermatic cord and pulmonary hilus. It most commonly arises in children and young adults, commonly females, but can occur at any age or as a congenital lesion.
Blue nevus presents as a solitary, blue to black dome-shaped lesion, usually about 1.0 cm in diameter. It may be due to arrested melanocytic migration from the neural crest. It is characterized by a dermal or submucosae proliferation of elongated, wavy spindle cells within the connective tissue or dense collagenous stroma. Cells can be arranged in nests and admixed with heavily pigmented melanophages. The pigmented bipolar dendritic cells do not display significant cytological atypia or mitotic figures. The overlying epidermis/mucosae lacks a junctional component.
Immunohistochemically, the melanocytes of blue nevus express S100, HMB-45 and Melan A (MART-1).
Non-neoplastic and inflammatory conditions resulting in cellular or extracellular pigment or post-hemorragic hemosiderin depositions can enter in differential diagnosis with blue nevus. Iron staining can be helpful in distinguish hemosiderin from Fontana-Masson positive melanin pigment.
1. Temple-Camp CR, Saxe N, King H. Benign and malignant cellular blue nevus. A clinicopathological study of 30 cases. Am J Dermatopathol. 1988;10(4):289-296.
2.Murali R, McCarthy SW, Scolyer RA. Blue nevi and related lesions: a review highlighting atypical and newly described variants, distinguishing features and diagnostic pitfalls. Adv Anat Pathol. 2009;16(6):365-382.
3.Buchner A, Leider AS, Merrell PW, Carpenter WM. Melanocytic nevi of the oral mucosa: a clinicopathologic study of 130 cases from northern California. J Oral Pathol Med. 1990;19(5):197–201.
4.Tannenbaum M. Differential diagnosis in uropathology, III—melanotic lesions of prostate: blue nevus and prostatic epithelial melanosis. Urology. 1974;4(5):617–621.
5.Zembowicz A, Mihm MC. Dermal dendritic melanocytic proliferations: an update. Histopathology. 2004;45(5):433–451.
Alessia Cimadamore (1), Rodolfo Montironi (2)
(1) Section of Pathological Anatomy, Polytechnic University of the Marche Region, School of Medicine, United Hospitals, Ancona, Italy; a.cimadamore@staff.univpm.it
(2) Molecular Medicine and Cell Therapy Foundation, Polytechnic University of the Marche Region, Ancona, Italy; r.montironi@univpm.it
Bladder
bladder; blue nevus; melanoma; hemosiderin;pigment