The first scenario presented pertains to a 41-year-old female whom had complaints relating to progressive deterioration in thoracic distress and shortness of breath over two months prior to hospital admission. Representative hematoxylin and eosin (H&E) staining of a postoperative biopsy are presented (Fig. 1). A tumorous growth was clearly identified as a discrete mass of hyperchromatic spindle cells with indistinct cytoplasm after H&E staining. The overall architecture appeared to be either diffuse or alternate hypo-/dense-cellular regions (Fig. 1A). The tumor tissue could therefore be assigned microscopically as a malignant schwannoma of variable cellular distribution with non-homogenous rhabdomyosarcomatous features (Fig. 1B). In addition, rhabdomyoblasts with a dense eosinophilic cytoplasm and cytoplasmic cross striations were observed scattered throughout the stroma and mainly comprised of pleomorphic spindle cells (Fig. 1C). The IHC assay was positive for S-100 protein, Myo-D1 and Desmin and when combined, these findings supported a diagnosis of MTT, comparable to previous studies.3
Further confirmation for MTT was derived from preoperative CT imaging scans of the chest region which revealed the presence of a distinctive and large non-MPNSTs/soft tissue sarcoma mass of size 7.7 cm × 6.0 cm located within the medial basal segment of lower lobe of the right lung (Fig. 2A). Additional imaging analyses obtained using contrast-enhanced CT scans of the thoracic region re-affirmed the presence of an irregular hemorrhagic or necrotic, well-circumscribed lobule (Fig. 2B). A low-density cyst was also evidenced by absence of mediastinal and hilar node enlargements in the surrounding region and a distinct septate demarcation within the cellular mass at the lesion periphery (Fig. 2B). The patient was not subjected to postoperative chemo or radiotherapy and after five months appeared to have recovered sufficiently with only minor refractory movement disorders, limb numbness, backache and dysuria discomfort were noted. Initially, long-term prognosis appeared to be positive, as postoperative re-examination of the chest area in CT scans revealed no recurrence of the mass-like shadow within the operative region. However, several well-defined and differentially sized homogeneous nodules were seen as persistent within the bilateral lungs which raised concerns of MTT metastasis and possible malignancy (Fig. 2C). Thus, further investigations of patient discomfort arising from clinical symptoms were performed through MRI upon the spinal cord. In these, a homogeneous tissue mass were observed to be expanding within the vertebral index at the 4th and 5th thoracic (T4-T5) segments causing microbleeds (Fig. 2D). Rather more radical anatomical consequences of MTT metastasis within thoracic region were also noted and included severe destruction of bone tissue on the right thoracic pedicle, plate and transverse processes of the T4 and T5 segments alongside tumor invasion of adjacent ribs, pleura and soft tissues (yellow arrow in Fig. 2D). Aside these, an outward dispersal of the lesion from the spinal dura mater and uncontrolled growth within the thoracic spinal cord were also observed (red arrow in Fig. 2D). Unfortunately, these symptoms were indicative of rapid multiple distal metastasis of MTT and the patient passed away two months later.
In a second scenario, a 37-year-old male presented with a persistent lower left quadrant dull abdominal pain over two months. There was a paternal familial predisposition of NF-1 inclusive of an uncle and grandfather. CT scanning of the abdominal region revealed the presence of a heterogeneous hemorrhagic or necrotic discoid mass 10 cm × 6.3 cm in size located within the left-side abdominal cavity (Fig. 3A). Calcifications were also evidenced in CT scans occurring at the margin of the cyst. In contrast-enhanced CT scans, the cyst margin was more prominent within the patient’s chest region (Fig. 3B) and similarities to the aforementioned case with the presence of a linear septum within the cellular mass were noted (white arrow, Fig. 3B). Furthermore, an irregular hypodense nodule was observed in between the T12 and the 1st lumbar (L1) vertebral canal interspersed with the left foramen intervertebral disc of the spinal cord (Fig. 3C). The lesion also resulted in significant compression of the adjacent vertebral bodies and adnexal bones and nodule elongation. Similar nodules also appeared posterior to the pancreas body and proximal to the right iliopsoas muscle and abdominal aortic branch (Figs. 3D and E, respectively). Originally the cyst was deemed to be a neurofibroma, however, resection, additional pathological analysis and positives for Desmin, Myo-D1 and S-100 protein IHCs were more consistent with a diagnosis of MTT.
The patient was not subjected to post-excision chemotherapy and radiotherapy, although be experienced progressive dysuria for a period of five months. Upon re-examination of the chest and abdominal regions by CT scans, multiple irregular nodules and masses within the abdominal cavity and retroperitoneal space were observed, consistent with a diagnosis of the recurrence of MTT (Fig. 4A). Once again, it was apparent that changes in cyst morphology, necrosis, hemorrhage and presence of septate lesions were, therefore, characteristics unique to MTT tumorigenesis. We noted that resurgence of tissue mass after excision was accompanied by invasion of the perirenal spaces and blockage of both ureters resulting in pelvicalyceal dilatation and hydronephrosis by enlargement of nodules in the perinephric space (yellow arrow, Fig. 4B). Tumor embolus features in bilateral iliac veins, postcava and right atrium were also observed (red arrow, Fig. 4B). In post excision contrast-enhanced CT scans of the chest area, the large, 5.2 cm × 3.2 cm well-defined lobulate mass adjacent to the right-side pulmonary hilum (Fig. 4C) appeared to be unchanged from preoperative conditions (Figs, 3C, D and E). The patient was subsequently discharged and the case followed up with a post clinical study. The two patients had been informed consent to publish this paper.