Rare primary malignant mixed Müllerian tumor of the mediastinum: A case report

Abstract

Rationale: Malignant mixed Müllerian tumor (MMMT) of extragenital organs is rare, especially in male. To our knowledge, this is the first reported case of primary MMMT at the mediastinum in male.

Patient concerns: A 54-year-old male was admitted to the hospital due to repeated stimulating dry cough for 2 years. His systemic examination was unremarkable. Laboratory workup revealed that all blood indicators were within normal limits. But subsequent computerized tomography (CT) scans of chest showed an abnormal soft tissue density in the area of its left, measuring approximately 4 cm in anterior-posterior dimension and 7 cm in maximum transverse dimension.

Diagnoses and interventions: The pathogenesis of these tumors remains controversial. The diagnosis is combined with biopsy and immunohistochemical staining. So, the patient underwent radical surgical resection and pathologic examination of the excised specimen was consistent with the diagnosis of MMMT. After surgery, he was treated by sequential chemoradiotherapy.

Outcomes: The patient died from tumor recurrence 16 months later.

Lessons: MMMT is a rare, highly aggressive tumor associated with interesting embryological origin, a definite diagnosis of which is only confirmed on pathological assessment. Due to its high degree of malignancy and high rate of recurrence, complete macroscopic excision of the tumor is recommended as soon as possible.

Figure 1

(A, B) Computed tomography of the chest showing an abnormal soft tissue density involving the left anterior mediastinum measuring 7 cm × 4 cm.

Figure 2

Tumor is variably cellular, consisting of spindle cells, showing prominent nuclear atypia and mitotic activity. Varying numbers of thick-walled arterioles are present (H&E, original magnification × 100).

Figure 3

H&E high-power view showing both malignant epithelial and mesenchymal elements. (A) (200×) H&E: showing squamous differentiation; (B) (200×) H&E: high power of malignant osteoid.

Figure 4

Immunohistochemistry: tumor cells are positive for keratin (A, 200×) and calponin (B, 200×) on the epithelioid components; tumor cells show strong diffuse expression for mesenchymal markers: vimentin (C, 200×) and S-100 (D, 200×).