1 Background

Granular cell tumors (GCTs) also called Abrikossoff's tumor are rare tumors of neurogenic origin, with preferential involvement of the mucous membranes, less frequently, in the viscera and skeletal muscles. It is mainly found in the craniocervical region [1, 2], rarely found in the external genitalia. To our knowledge, 19 cases in the penis have been reported [3]. In this article, we report the case report of a purely cutaneous case of rare clinical presentation in the penis.

2 Case presentation

A 54-year-old man, with no history, consulted for a lumpy lesion of the penis which had been evolving for a year in a context of maintenance of general condition.

Clinical examination revealed a lumpy skin plaque on the penis, indurated, 3 cm in large diameter (Fig. 1), painless and mobile in relation to the deep plane. The lymph node areas were free, and the remainder of the skin examination was without abnormalities.

Fig. 1
figure 1

Lumpy lesion on the lateral aspect of the penis

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An excisional biopsy of this tumor lesion was performed, the anatomopathological study showed that the superficial dermis arbites a tumor proliferation made up of large clumps of cells, eosinophilic and with a nucleus devoid of cytonuclear atypia (Fig. 2), the immunohistochemical study was positive for the S-100 protein (Fig. 3). The current follow-up is one year, without recurrence (Fig. 4).

Fig. 2
figure 2

Superficial dermis harbors a tumor proliferation made up of clumps of large, eosinophilic cells with a nucleus devoid of cytonuclear atypia

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Fig. 3
figure 3

The positive immunohistochemical study for the S-100 protein

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Fig. 4
figure 4

Appearance of the penis after tumor resection

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3 Discussion

Granular cell tumors (GCTs) are rare, usually benign, slow-growing tumors of unclear origin. The peak incidence occurs between the ages of 40 and 60 years [4], although several cases of children have been published. Women are more commonly affected than men, and blacks more than whites, occurring more frequently in the head and neck area, with the tongue considered the most common site. However, GCTs of the external genitalia, particularly the penis, have been rarely reported.

GCT was first described in 1926 by Abrikossoff [5], who called these tumors “granular cell myoblastomas,” suggesting that their origin was from skeletal muscle. Additional studies have demonstrated their close association with peripheral nerves [4]. Later, the use of electron microscopy and immunohistochemical techniques provided further evidence supporting the differentiation of Schwann cells from these tumors, which later became known as GCT. The staining patterns support a neural origin, in particular a neural sheath or a Schwann cell origin for GCT. They are generally positive for S-100, vimentin, neuron-specific enolase and Leu-7. In addition, they are negative for actin, glial fibrillary acidic protein, neurofilament, and cytokeratin [6,7,8].

The treatment of granular cell tumor is a surgical treatment [5]; it allows a definite diagnosis by the anatomopathological examination of the excision piece which must look for the limits of excision and the presence of criteria of malignancy. The patient is considered cured after this local excision, except in the following cases [2]:

  • Tumor with multiple lesions.

  • Tumor measuring more than 4 cm

  • Invasion into adjacent tissues.

  • Tumor with rapid growth

  • Tumor with local recurrence.

  • Female sex

These tumors require close subsequent monitoring because they present a risk of malignancy and recurrence. Their evolution is often favorable if the surgical resection is complete. However, in the event of incomplete tumor resection, tumor persistence or tumor recurrence is inconsistent [1].

4 Conclusions

Granular cell tumors (GCT) also called Abrikossoff's tumor are rare tumors of often benign neurogenic origin, mainly located in the craniocervical region, rarely found in the external genitalia, the diagnosis is based on the anatomopathological study completed by immunohistochemistry, and treatment consists of complete surgical excision of the tumor.