Prepubertal intratesticular keratocyst. Case report and literature review

BACKGROUND: Testicular epidermoid cysts (TEC), also known as keratocysts, are rare lesions accounting for 1% of all testicular masses4,9,11. Most of them are incidentally discovered and radically treated5,8,9. Clinically they present as firm palpable mass highly undistinguishable from other testicular cancers. Scrotal sonography (US), contrast enhanced ultrasound (CEUS) or magnetic resonance (MR) describe the lesion1,2,8 but diagnosis depends on histology. Although no cases of metastases have been reported to date in literature7 ,the real understanding of biological behaviour and clinical management is unresolved2,3. We report the case of a young patient affected by testicular keratocyst who underwent to surgical enucleation. By describing this case we also reviewed literature about histologic features of pre-pubertal form and the feasibility and safety of this procedure. CASE REPORT: A 16 y.o. caucasian male presented for a firm mass recently discovered on self examination. Anamnesis was uneventfull for genital infections or trauma: no familiarity for testicular cancer was reported. The right testis presented with a palpable painless mass in the middle portion of the testis, entirely covered by normal parenchima. Inguinal and supraclavicular lymph nodes were negative and serum markers (AFP, bHCG, PLAP and LDH) too. Scrotal sonography (US) reported a well circumscribed 2 centimetres mass within the right testis with intervening septa and coexisting solid areas: intralesional calcifications were not described. Intralesional vascularity was ruled out on ecodoppler. MR was negative for secundarisms; furthermore the exam did not reveal any intralesional contrast enhancement, totally suggesting a bening lesion. Testicular biopsy was offered. RESULTS: Frozen section was suggestive for mature keratocyst and surgical enucleation was offered. The lesion presented macroscopically as a 20 x 22 x 25 millimetres mass highly indishinguable from any malignant neoplasms. And totally covered by normal testicular parenchima. On microscopic evaluation the lesion was composed by horny material well delimited by a cystic wall (Fig.1) of squamous epithelium. No association with Intratubular Germ Cell Neoplasms (IGCN) was found nor cellular atypia or mitotic activity. Definely it was classed as pre-pubertal mature intratesticular epidermoid cyst. DISCUSSION: TEC are benign tumors which arise from ectoderm, endoderm or mesoderm tissues4,9,11. They account for around 1-2% of all testicular masses4,9,11 and tipically present in mid-adulthood. Caucasian males are more involved. The etiology is still debated2,3 (Cakiroglu B.; Cook). Two main form of TEC have been described in literature: pre-and post-pubertal. Pre-pubertal TEC have been historically considered as benign lesions since no association with germ cell neoplasm in situ (GCNIS) have been reported nor cases of metastasic spread. Histology often rules out unfavorable prognostic features such coexisting lesions or association with germ cell neoplasms. Due to this reason, they have been names “simple testicular epidermoid cyst”. Clinically, they are as highly indistinguishable to all testicular cancers and often presenting as a firm, painless palpable mass within the testis: the right testis seems to be more involved than left (Kenan). Serum markers are always negative too7 (Kenan). US may guide diagnosis since these lesion show typical radiographic features: a well marginated intratesticular masses with a lamellar ‘onion skin’ or ‘bull-eye’ pattern and avascular centre1,2,8 might always suggest testicular keratocyst (Cakiroglu; Muoka; Anheuser). CEUS also provides with more informations ruling out intralesional vascularity. MR imaging better describes the tumor, rules out secundarism or local infiltration and evaluates the absence of contrast enhancement which further suggest a benign nature. Although these features can guide clinical orientation, diagnosis only depends on histology: differentiation from coexisting enthities such as pure teratomas, germ cell tumors (GCT) or granulomatous disease is mandatory also in pre-pubertal forms. Uncommon features such as cellular atypia, mitotic activity, necrosis, hemorrhage and epythelial hyperplasia need to be missing also in these forms5,6,11 (Umar; Dockerty; Ewen). Partial orchiectomy or testis-sparing excision with frozen section is becoming day by day the standard treatment2 (Carikoglu et al); however, as the final pathology report describes a teratomatous lesion or malignant features, further radical orchiectomy is required. In our case the patient underwent contrast enhanced MR at 6 and 12 month which ruled out any visceral or lymph nodes metastases. Ultrasound of the testis excluded local recurrence. CONCLUSION: Testicular keratocysts are rare lesions commonly presenting in young male and clinically indistinguishable from other testicular lesion. Pre- and post-pubertal form represent the two main variants. Biologic behaviour and clinical management is still unresolved. Pre-pubertal variants are not related to IGCNIS or unfavorable histologic features; no cases of spreading have been reported to date and they are considered benign tumors. Serum markers, CEUS and MR may be helpful in making diagnosis and surgical planning. Only histology confirms the nature of the lesion ruling out coexisting histotypes. The importance of accurate diagnosis is crucial for preventing unncessary orchiectomy: testicular sparing surgery should be offered.