title: Granular cell tumor of the penis: clinicopathologic evaluation of 9 cases.
abstract: The occurrence of granular cell tumor (GCT) in penile tissue is very rare, with only 9 examples reported to date in the English-language literature. Herein, we describe the clinicopathologic and immunohistochemical findings in 9 additional cases. The patients ranged in age from 20 to 60 years (mean, 42 years; median, 40 years) at time of diagnosis. All penile tumors were solitary and arose in the dermis of the penile shaft (n=4), prepuce (n=3), and corona (n=2). A patient had a history of multiple cutaneous GCTs. Duration of symptoms before surgery ranged from 5 days to 2 years with the presence of an asymptomatic nodule representing the most common tumor-related complaint (n=8). The lesions ranged in size from 0.6 to 2.5 cm (mean, 1.5 cm; median, 1.5 cm). Microscopically, the tumors were moderate to highly cellular and were composed of oval to polygonal-shaped cells with abundant coarsely granular eosinophilic cytoplasm. Tumor cells grew in infiltrating nests, cords, and trabeculae and showed neural (n=2) and vessel wall (n=1) invasion or formed a relatively well-marginated solid nodule. Bland cytological features with only rare cells showing nucleomegaly (n=7) or spindling (n=3) were exhibited by 8 tumors. A tumor demonstrated diffuse nuclear atypia and was classified as "atypical." Mitotic activity ranged from 0 to 8 mitoses (mean, 1.4 mitoses) per 50 high-powered fields with no atypical division figures identified. All tumors tested showed moderate to strong immunohistochemical expression of S100 protein (n=6) and low-affinity nerve growth factor receptor (n=5), which was useful for detecting small deposits of tumor and helpful in evaluating surgical margins. Focal tumor cell immunoreactivity was observed for calretinin (4/6 cases) and glial fibrillary acidic protein (1/6 cases). All patients underwent simple (local) excision of their tumor. Complete follow-up data (mean, 21 years; interval range, 0.5-28 years) were available for 6 patients. No patient experienced recurrence or metastatic spread of tumor although surgical margins were microscopically involved by tumor in 5 cases. Benign GCT involving superficial soft tissue of the penis can be adequately managed by a simple excision. Patients with microscopically involved surgical margins can be clinically followed without immediate additional surgery.
authors.affiliation: Department of Pathology, Feinberg School of Medicine, Northwestern Memorial Hospital, Chicago, IL 60611, USA. wbl769@northwestern.edu
authors.forename: William B
authors.initials: WB
authors.lastname: Laskin
authors.forename: John F
authors.initials: JF
authors.lastname: Fetsch
authors.forename: Charles J
authors.initials: CJ
authors.lastname: Davis
authors.forename: Isabell A
authors.initials: IA
authors.lastname: Sesterhenn
mesh_terms: D000328:Adult; D064032:Calbindin 2; D002467:Cell Nucleus / Q000473:pathology; D003593:Cytoplasm / Q000473:pathology; D005904:Glial Fibrillary Acidic Protein / Q000032:analysis; D016586:Granular Cell Tumor / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D010412:Penile Neoplasms / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D020800:Receptor, Nerve Growth Factor / Q000032:analysis; D064030:S100 Calcium Binding Protein G / Q000032:analysis; D009418:S100 Proteins / Q000032:analysis; D016896:Treatment Outcome
chemical_list: C576764:CALB2 protein, human; D064032:Calbindin 2; D005904:Glial Fibrillary Acidic Protein; D020800:Receptor, Nerve Growth Factor; D064030:S100 Calcium Binding Protein G; D009418:S100 Proteins