Malignant melanoma presenting as isolated thoracic spinal metastases- Case report

Abstract

Introduction

Malignant melanoma is a highly invasive tumor with very poor prognosis. Common metastases of MM are noted in lungs, Central nervous system, liver, lymph nodes and isolated spinal metastases are extremely rare. To our knowledge only one case of isolated lumbar spinal metastases of MM was reported.

Case presentation

An 80-year-old female presented with pain at upper thoracic spine and progressive weakness of bilateral lower limbs. She gives history of recurrent MM of nose, for which she underwent excision of tumor twice. On examination she had spastic gait with exaggerated lower limb reflexes and lower limb motor grade of 3/5. The MRI scan of thoracic spine revealed lobulated enhancing mass involving the right half of the T3 vertebral body and corresponding posterior elements. The patient underwent palliative spinal decompression and excision of tumor. Histopathology confirmed MM. The PET scan done post operatively ruled out any other sites of metastases.

Discussion

Though the incidence of isolated manifestation of spinal metastases of MM is extremely rare, clinical suspicion and advanced imaging can help to diagnose early. The treatment strategy should be guided by current neurological status, nature of the tumor, presence of mechanical instability and patient's fitness to undergo surgical intervention.

Conclusion

Patient diagnosed with MM should be closely followed up even in absence of any recurrence at the primary site. Surgical decompression can improve neurological symptoms and decrease pain to improve quality of life even at advanced stage of the disease.

Highlights

• •Isolated spinal metastases of malignant melanoma are extremely rare.
• •High clinical suspicion and advanced imaging is key to early diagnosis in a patient with positive history of primary melanoma.
• •Palliative surgical decompression is the treatment strategy to improve neurological weakness, decrease pain and improve quality of life.
• •For patients with diagnosed MM, very close lifetime follow up and clinical observation is important.

1. Introduction

Spinal metastases of MM are rare with reported incidence of 2.4 % and isolated spinal metastases in absence of metastases to other organs are even rarer [1]. To our knowledge only one case of isolated lumbar spinal metastatic melanoma was reported [2]. The presence of spinal metastases represents the late event of evolution of the disease with overall median survival of 4 %, 2-year survival of 0.2 % and five-year survival of 0% [1,3,4]. Advanced imaging and biopsy can help to confirm and diagnose metastases for early intervention.

The goals of treatment of spinal metastases are pain relief, restoration or preservation of neurological function, stabilization of spinal segment and improvement of health related quality of life [17]. Treatment decision is based on Algorithm for Spinal Metastases developed by Boriani's group and NOMS decision framework [18]. The key factors that should be taken into consideration for treatment are overall medical status of the patient, presence of neurological deficits, presence of spinal instability and nature of the primary tumor. In the presence of neurological symptoms, surgical resection is the first line treatment option [2]. Surgical resection and decompression can help to improve neurological function, relief pain and improve quality of life [5]. The surgical resection helps to improve the symptoms by reducing mass effect of the tumor [6]. The recent advent of immunotherapy has shown some favorable increase in progression free survival, but more studies are required to ascertain this [[7], [8], [9]].

2. Method

The information in this case report is obtained from retrospective chart review and is reported in line with SCARE guideline [10]. Patient's informed written consent was obtained to use data for publication of this case report.

3. Case report

An 80-year-old female presented with chief complaint pain at upper thoracic spine for one month and weakness of bilateral lower limbs for three days. She developed gradual onset and progressive pain in her upper thoracic spine, the pain was persistent in nature even at rest and while sleeping. The pain intensity worsened over time and at the presentation the pain severity was VAS (Visual analogue score) 9/10. The weakness of bilateral lower limbs was gradual onset and progressive in nature. She denied history of bladder and bowel dysfunction. She was diagnosed with recurrent cutaneous melanoma over the tip of her nose two years ago and underwent tumor excision twice by Otolaryngologist six months apart. The histopathology report of two samples obtained during each surgery confirmed malignant melanoma. Following the last surgery there was no recurrence reported at primary site.

On physical examination, she was afebrile, a previous surgical scar was noted over the tip of her nose, on systemic examination no lymphadenopathy and palpable mass was noted. Focus examination revealed mild tenderness over dorsal spine at T3 level with no obvious palpable mass. Her gait was spastic, upper limb neurological examination was normal. Lower limb examination revealed increased tone, muscle power of 4/5 in both lower limbs, reflexes were 3+, Babinski sign was extension and sensation including perianal sensation were intact. On day two of admission, her lower weakness progressed to 3/5 and was not able to walk and she developed acute urinary retention and loss of bladder sensation.

The laboratory investigation revealed normal WBC-5.50 (4.21–10.29 × 10^×3/μl), ESR-42 (0.0–15 mm/h), CRP-0.60 (0.00–6 mg/l), Serum creatinine-0.8 (0.4–1.0 mg/dl), CEA-3.82 (0.0–5.20 ng/ml), CA125–8.13 (0.0–35 U/ml), CA 19-9- 11.49 (0.0–37 U/ml) and urine Bence Jones Protein was negative. The MRI scan of thoracic spine revealed lobulated enhancing mass involving the right half of the T3 vertebral body, its pedicle, lamina & transverse process on the right side measuring 4.2 × 4 cm causing significant canal stenosis. The lesion appeared hypointense in both T1 and T2 weighted images with contrast enhancement. No significant adjacent pre or para vertebral soft tissue involvement was noted. A multilevel degenerative cervical canal stenoses were noted however there was no lesion in rest of the spine (Fig. 1). CT (Computed Tomography) scan of chest and abdomen revealed no lesions at chest, abdomen or lymph nodes.

Fig. 1.

a. MRI scan of cervicothoracic spine, T1 weighted image of sagittal view showing hypointense signal intensity of anterior two third of T3 vertebra involving corresponding posterior elements.

b. T2 weighted sagittal image showing hypointense signal at the same region.

c. The post contrast T1 sagittal image showing diffuse heterogeneous enhancement of the lesion.

d. The post contrast T1 axial image showing contrast enhancement involving mainly right side of T3 vertebra and corresponding posterior elements.

A provisional working diagnosis of T3 spinal tumor with thoracic myelopathy, mJOA 14/18 and Nuric score of 3 was made. In view of presence of T3 vertebral lesion with progressive weakness of lower limbs, patient was taken up for emergency spinal decompression, excision of lesion and biopsy. T3 laminectomy and excision of tumor was done. Intraoperatively a tar like soft tissue mass was noted extending from T2-T4 level mostly on right side involving right T3 lamina, transverse process, pedicle and posterior 2/3rd of T3 vertebra. Near total excision of tumor was achieved and soft tissue and bone samples were sent for histopathology. Histopathology showed atypical melanocytic cells having round to oval nuclei with prominent nuclei and abundant cytoplasm containing melanin pigment arranged in sheets. Frequent Mitoses were noted with focal area of bone marrow (Fig. 2). Combined with the immunohistochemical results, this finding was consistent with that of metastatic MM. She underwent supervised rehabilitation of lower limb strengthening and gait training. After her surgical wounds were healed, she was referred to Tata Medical Center, Kolkata for further evaluation of the extent of the disease and adjuvant therapies. At the time of referral, her lower limb motor was 4/5 and she was still not able to void urine and sent with urinary catheter insitu. Patient underwent PET scan two weeks after surgery at Tata Medical Center. The PET scan report revealed the evidence of post- surgical uptake at the operated site and didn't reveal metastases to any other part of the body. The patient was offered adjuvant chemo and radiation therapy, however the patient and relatives opted not to avail further treatment.

Fig. 2.

a. H&E sections showing proliferation of atypical melanocytes at ×100 magnification.

b. H&E sections show higher magnified view of melanoma.

c. H&E sections of melanoma cells involving the bone marrow cavity.

Patient was followed up monthly at our orthopedic outpatient department and at one month postoperative follow up, her lower limb motor was 5/5 and she was able to walk independently. She had regained bladder sensation but was still not able to void urine freely. She underwent supervised bladder training. Her pain improved from VAS 9 to 2. At three months follow up she was able to freely void urine and Foley's catheter was removed.

4. Discussion

Metastatic spinal melanoma is a rare and aggressive disease with poor prognosis [1]. The median time of spinal metastases is reported to be approximately 3.5 years [4]. The most common primary site is cutaneous melanoma followed by unknown primary [1,4]. Ocular and mucosal melanomas are also reported. The commonest site of metastases is lungs, liver, CNS, lymph nodes, bones and spine [1,11]. Spinal metastases are commonly reported in thoracic followed by lumbar spine [1,3,11]. In this case spine is the initial manifestation of metastases without involvement of other body parts. Pain (75–82 %) and neurological deficits (17–21 %) are the most common clinical presentation of spinal metastases of MM [4,11]. This patient also predominantly presented with pain and progressive weakness of lower limbs.

Clinical suspicion and advanced imaging are required for early diagnosis of metastases. MRI scan is commonly used imaging modality. Bone scintigraphy is another option for whole body screening. However, bone scintigraphy may miss osteolytic lesions [12]. On MRI, the typical finding in metastatic spinal melanoma is lesion with accompanying vasogenic edema, typically hyperintense on T1 sequence and hypointense on T2/FLAIR, with post-contrast T1 imaging demonstrating either peripheral rim enhancement or diffuse heterogenous enhancement [13]. The differential diagnosis that should be considered are Lymphoma, Leukemia, Kaposis sarcoma and other hypervascular metastatic diseases which have similar MRI findings [16]. In this case since the patient had history of recurrent cutaneous melanoma, we had high suspicion of spinal metastases and MRI scan helped to further narrow down our differential diagnosis.

Treatment principles of metastatic spinal melanoma are similar to other spinal metastases [11,14]. Currently NOMS decision framework helps to plan appropriate treatment options for patients with spinal metastases. The presence of metastatic epidural spinal cord compression is an indication for surgical intervention. The Spinal Instability Neoplastic Score help to determine spinal instability and requirement for spinal stabilization procedure in addition to decompression. Since melanoma is resistant to chemo and radiotherapy, surgical resection is the mainstay of treatment to improve the quality of life. However, the role of surgery to improve survival is poorly understood due to the limited number of cases reported [15]. Tomita scoring system guides treatment strategy and helps to understand overall prognosis [5]. In 2001 Tomita proposed scoring system to predict survival in spinal metastases. It consist of three parameters, the speed of tumor growth, absence or presence of visceral metastases and number of metastatic bony lesion. The score of 2–4, 4–6, 6–8 and 8–10 has predicted prognosis of more than 2 years, 1–2 years, 6–12 months and less than 3 months respectively. Accordingly a score of 2–4, 4–6, 6–8, and 8–10 are recommended wide or marginal excision, marginal or intra-lesional excision, palliative surgery and supportive care respectively [5]. The goal of the surgery is to relieve pain, improve neurological weakness and improve quality of life. To improve prognosis and survival, surgical treatment with adjuvant radiation and systemic therapy is recommended. This patient has a Tomita score of 7 with predicted survival of 6–12 months. There was moderate spinal instability with SINS score of 9. Considering her rapidly growing nature of tumor with progressive neurological deficits and moderate spinal instability and expected survival of 6–12 months, palliative surgical decompression without spinal stabilization option was offered to the patient. Since total resection of tumor was impossible, patient was advised to undergo postoperative adjuvant radiation and chemotherapy. However, the patient and relatives opted not to undergo chemo and radiation therapy.

Postoperatively patient had clinical improvement, her pain has decreased from VAS 9 to 2. Her lower limb motor has improved, and she was able to walk independently.

5. Conclusion

We present a very rare case of isolated thoracic spinal metastases of malignant melanoma. Clinicians should have a high degree of suspicion of spinal metastases in patients who had a history of primary malignant melanoma when presented with pain and progressive weakness. Even at the advanced stage, surgical decompression can help to improve quality of life and live pain free period.

Abbreviations

CBC

Complete Blood Count

CEA

Carcinoembryonic antigen

CNS

Central Nervous System

CRP

C-reactive Protein

CT

Computed Tomography

ESR

Erythrocyte Sedimentation Rate

MESCC

Metastatic epidural spinal cord compression

mJOA

Modified Japanese Orthopedic Association

MM

Malignant Melanoma

MRI

Magnetic Resonance Imaging

NOMS

Neurologic, oncological, mechanical and systemic

PET

Positron Emission Tomography

SINS

Spinal instability neoplastic score

VAS

Visual analogue score

WBC

White blood cell

Consent

Informed written consent was obtained from the patient for publication of this case report.

Ethical approval

Ethical approval was not necessary from the institute for case report.

Funding

No funding was sought for this study.

Author contribution

Letho: Data collection, manuscript writing, study concept and design.

Birendra Pradhan: Manuscript writing and data collection for Histopathology reports.

Guarantor

Ugyen Thinley.

Research registration number

IJSCR_109921

Conflict of interest statement

Authors declare no conflict of interest related to this case report.