Epidermoid cyst of the adult testis. Case report and literature review

BACKGROUND: Testicular epidermoid cysts (TEC) are rare lesions often incidentally discovered and radically treated. They present as testicular firm palpable mass. Ultrasound and MR may be useful in characterizing the lesion. Diagnosis depends on histology. The real understanding of biological behaviour and clinical management is unresolved. We report the case of a young male who underwent to surgical keratocyst enucleation. CASE REPORT: A 16 y.o. male presented for a firm mass in the testis. The right testis presented with a palpable painless mass in the middle portion. Inguinal and supraclavicular lymph nodes were negative. Serum markers (AFP, bHCG, PLAP and LDH) were normal. Scrotal sonography (US) reported a well circumscribed 2 centimetres mass with intervening septa and coexisting solid areas: intralesional calcifications were not described. Magnetic Resonance (MR) ruled out secundarisms and intralesional contrast enhancement. Biopsy with was offered. RESULTS: Frozen section was suggestive for mature keratocyst and surgical enucleation of the mass was offered. DISCUSSION: TEC are benign tumors which arise from ectoderm, endoderm or mesoderm tissues. They account for around 1-2% of all testicular masses and tipically present in mid-adulthood. The etiology is still debated and whether these should be classed as a variant of mature teratoma is still under discussion. Simple TEC correspond to the prepubertal-type teratoma of the 2018 WHO classification and are unrelated to germ cell neoplasm in situ (GCNIS). Post-pubertal variant may be more frequently associated with invasive GCT and should be radically treated especially when bad prognostic features coexist: due to this reason the are identifyed as complex TEC. Clinically keratocysts are highly indistinguishable to all testicular neoplasms. Serum markers are negative too. Sonographic study (US) may guide diagnosis: they present as non-vascular, well marginated intratesticular masses with a lamellar ‘onion skin’ or ‘bull-eye’ image and avascular centre. Contrast enhanced ultrasound (CEUS) and Magnetic Resonance (MR) also provide with more informations since the absence of contrast enhancement highly suggest the benign nature of the lesions. Diagnosis only depends on histology: differentiation from coexisting enthities such as teratomas, germ cell tumors (GCT) and granulomatous disease is mandatory also in pre-pubertal forms. Microscopically, cellular atypia, mitotic activity, necrosis, hemorrhage and epythelial hyperplasia are usually missing in pre-pubertal ones totally suggesting a benign behaviour. Moreover, no case of recurrence or metastases have been to date reported in literature: partial orchiectomy or testis-sparing excision with frozen section is becoming day by day the standard treatment. CONCLUSION: Testicular keratocysts are rare lesions commonly presenting in young male and indistinguishable from other testicular lesions. Pre- and post-pubertal form represent the main variants. Biologic behaviour and clinical management is still unresolved. Pre-pubertal form are not related to IGCNIS and no cases of spreading have been reported to date: differently from post-pubertal ones they are considered benign tumors to date. Serum markers, sonographic features and MR may be helpful in making diagnosis and surgical planning. Only histology confirms the nature of the lesion and ruling out coexisting histotype. The importance of accurate diagnosis is crucial for preventing unncessary orchiectomy since testicular sparing surgery shoudl be offered.