A Rare Case of Azoospermia Due to Isochromosome Yp: Robotic Excision of Associated Mullerian Duct Cyst and Review of Clinical Implications

E. Kaplan-Marans, C. Edwards, Y. Katlowitz, M. West, N. Leelani, G. DeMeo, D. Silver, J. Khurgin

Isochromosome Yp, Azoospermia, Infertility, Mullerian Remnant, Mosaic Monosomy X

Introduction:
Isochromosome Yp is a rare structural chromosomal abnormality that results from the duplication of the short (Yp) arm and the partial or complete loss of the long (Yq) arm of the Y chromosome. This abnormality leads to individuals typically retaining the sex-determining region Y (SRY) gene responsible for initiating male sex differentiation but lacking the azoospermic factor (AZF) gene region required for spermatogenesis.

Objectives:
To present a rare case of azoospermia secondary to isochromosome Yp with 45,X mosaicism, highlight the robotic excision of an associated Müllerian duct cyst, and review the normal embryology, underlying pathophysiology, clinical implications, and management of this sex chromosome abnormality.

Methods:
Relevant history obtained retrospectively from patient chart. Surgical video of the cyst excision was obtained via the C-SATS platform. A literature review was performed to contextualize explore the incidence, pathophysiology, phenotypic variability spectrum,  and oncologic risks associated with management options for this rare this chromosomal anomaly.

Results:
We report the case of a 40-year-old male with primary infertility and hematospermia. His medical history included right cryptorchidism with orchiopexy at age four and hypospadias repair at age 12. Two semenalyses revealed azoospermia. Cross-sectional imaging revealed a large midline pelvic cyst arising from the prostate. Karyotype analysis demonstrated isochromosome Yp with 45,X mosaicism. The presence of the SRY gene led to his testicular development, while the absence of the AZF region caused his azoospermia. Robotic-assisted excision of the Müllerian duct cyst was performed.

Conclusions:
Isochromosome Yp is a rare chromosomal abnormality associated with infertility.  Patients with this disorder can encompass a broad spectrum of phenotypic characteristics. Without the AzF region, there is no chance of sperm retrieval. Options for children include donor sperm and adoption.

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