An Unsuspected Histological Finding in a Patient with Cancer and AKI

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Case Description

A 54-year-old patient presented to the hospital with AKI after receiving chemotherapy. The patient was diagnosed with lymphogenic metastatic squamous cell carcinoma of the glans penis 2 years earlier. At diagnosis, partial amputation of the penis with inguinal lymphadenectomy was performed followed by adjuvant chemotherapy with cisplatin, 5-FU, and paclitaxel. However, inguinal, iliacal, and para-aortic relapses and bone metastasis occurred. Subsequently, several salvage chemotherapies, including pembrolizumab for checkpoint inhibition due to high PD-L1 expression, were administered. Laboratory studies showed a serum creatinine of 6.75 mg/dl (reference range 0.7–1.2 mg/dl).

Thus, a percutaneous kidney biopsy was performed for diagnostic and prognostic purposes. A periodic acid–Schiff–stained kidney section showed a moderate, diffuse, potentially partially reversible tubular damage, most likely originating from drug toxicity (Figure 1A). Additionally, in one dilated glomerular capillary, a small group of atypical polygonal cells with intercellular bridges and enlarged nuclei stood out, likely representing a hematogenous micrometastasis of the squamous cell carcinoma (Figure 1A, insert). Figure 1B shows a periodic acid–Schiff–stained section of the original tumor.

Figure 1.

Histological findings in kidney and carcinoma sections. (A) Periodic acid–Schiff (PAS)-stained kidney section (original magnification ×200) showed a moderate, diffuse, potentially partially reversible tubular damage. In one dilated glomerular capillary, a small group of atypical polygonal cells with intercellular bridges and enlarged nuclei stood out. The insert shows the atypical cells in higher magnification (black arrow, original magnification ×400). (B) PAS staining of the original tumor shows the similarity of the carcinoma cells found in the glomerular capillary and the tumor tissue (original magnification ×400).

Discussion

In the following course, kidney function worsened, and despite the unfavorable prognosis, dialysis was initiated at the request of the patient and his family. The patient died of tumor-related sepsis 3 weeks after detection of glomerular micrometastasis—a time course faster than predicted by involved oncologists but in line with reference values in the literature (1). An autopsy study of ten patients with widespread metastatic penile cancer showed renal infiltration in four cases, being the fifth most frequent site of metastasis after the liver, lungs, systemic lymph nodes, and heart (2). In general, kidney metastasis of primary nonrenal cancer is relatively uncommon—an interesting finding, considering the high blood flow to which the kidney is exposed (3). In autopsy studies of patients who had died from malignant disease, kidney metastases were found in about 7%, originating in descending frequency from tumors of the lung, breast, and skin (melanoma) and of the genitourinary, gastrointestinal, and gynecologic tracts (4).

Altogether, glomerular micrometastasis of squamous cell carcinoma in a glomerular capillary is rarely seen. Awareness of such a finding is critical for accurate histopathologic diagnosis in patients presenting with simultaneous kidney dysfunction and metastatic cancer disease and prognostically important as a sign of advanced metastatic dissemination with poor outcome, which should be taken into consideration when deciding on therapeutic strategy.

Teaching points

• Glomerular micrometastasis of squamous cell carcinoma in a glomerular capillary can occur in patients presenting with simultaneous kidney dysfunction and metastatic cancer disease.

• Glomerular micrometastasis is a sign of advanced metastatic dissemination with poor outcome.

Disclosures

U. Wenzel reports honoraria from Bayer and Novartis, and an advisory or leadership role for Neuroloop. T. Wiech reports being an employer of the Institut für Pathologie, Universitätsklinikum Hamburg-Eppendorf, Germany; honoraria from Bayer, GlaxoSmithKline GmbH, and Novartis; and an advisory or leadership role for Retrophin. The remaining author has nothing to disclose.

Funding

T. Wiech and U. Wenzel received funding from Deutsche Forschungsgemeinschaft.

Author Contributions

F.E. Hengel and U. Wenzel wrote the original draft of the manuscript; F.E. Hengel and T. Wiech were responsible for visualization; U. Wenzel was responsible for supervision; and all authors were responsible for the conceptualization; reviewed and edited the manuscript; and were involved in the clinical care of the patient.