Cervical Osteoma in Hereditary Multiple Exostoses.

Osteoid osteoma is a benign bony pathology. It presents either as a solitary lesion or as multiple lesions with a genetic predisposition. Reported more often in teenagers with thrice more common incidence among boys than in girls, it has a predilection for long bones of lower limbs. Less commonly arising from iliac crest or ribs; it is seen to be further rare to have originated from vertebrae or tarsal/carpal bones. Cranial osteomas are detected either incidentally on imaging or present as a bony hard swelling arising from the skull. Spinal intracanal osteomas are extremely rare to encounter in clinical practice. Cervical intracanal lesion in a case of hereditary multiple exostoses (HME) presenting with myelopathy is further rare. Less than thirty such cases have been reported so far. We present here a rare case of HME in a 16-year-old boy with compressive myelopathy secondary to intracanal cervical osteoma at C4 Lamina and spinous process. He had a phenotypical expression of hereditary multiple osteomas with a strong family history of inheritance of trait among first-degree male relatives favoring genetic transmission of disease with variable penetrance. All reported cases, to date, are discussed in a tabulated form. Copyright:

CASE

A 16-year-old-boy presented with complaints of the stiffness of all four limbs for the last 2 months. To begin with, stiffness started with his right lower limb and gradually progressed to involve the rest of the three limbs. He also developed difficulty in initiation of micturition lasting 3 weeks. There was no history of head/spine injury in past, neck pain, fever, weight loss, facial asymmetry, change in speech, or difficulty in swallowing.

Of importance, he had multiple bony hard swellings all over the body for the last 8 years. On enquiring, he recalled that the first swelling to have arisen was in right shin 8 years back. Similar bony hard swellings were subsequently noted in the left calf and left scapula, which was soon followed in the right pelvis and multiple digits of both hands. Born out of the nonconsanguineous marriage of his parents, the patient had two brothers and three sisters. None of his sisters, but both of his brothers, had similar phenotypical features of multiple bony swellings arising from different bones spread all over their bodies. Son of his elder brother also suffered from this illness. None of his male relatives had symptoms suggestive of spinal compressive myelopathy; in fact, two of his brothers had experienced spontaneous regression of their extra-spinal swellings throughout the illness. Pedigree suggests a Y-chromosome related inheritance with variable penetrance of the trait.

On general physical examination, the patient was averagely built and moderately nourished with no evidence of cranial/spinal deformity. There were no features of neurocutaneous markers like hypopigmented patches or firm subcutaneous neurofibromas. However, he had multiple bony hard noncompressible swellings densely adhering to underlying bones. These swellings were noted at the left scapula, left calf, right tibia, right pelvic bone, and multiple phalanges of both hands, as seen in Supplementary Figure 1. Neurological examination discloses motor weakness of all four limbs with the power of 3/5 on MRC grade. He was not able to stand or walk, not even with support. On sensory examination, he had bilaterally symmetrical graded sensory loss below the seventh cervical dermatome. Pathological reflexes like Hoffman and Babinski reflex were present bilaterally. The patient was evaluated with computed tomography (CT) and magnetic resonance imaging (MRI) of the cervical spine with whole spine screening. MRI cervical spine [Figure 1A and B] reveals T1- as well as T2-hypointense lesion arising from the posterior element of C4 vertebrae and protruding into the spinal canal at this level to make it significantly stenosed. Pathology was in exact anatomical and signal continuity of the fourth cervical vertebrae’s bony posterior element. Spinal cord was critically compressed and shows signal changes in favor of focal myelomalacia extending from the lower border of C3 to the lower border of C6. CT Cervical spine [Figure 2AC–C] confirms this bony lesion as a broad-based cortical pathology originating from the ventral surface of the spinous process of C4 and protruding into the spinal canal to occupy almost eighty percent of canal space. On screening the rest of the spine, there was no evidence of lesion anywhere else except at C4. He was also evaluated with X-rays for various bony swellings [Supplementary Figure 2].

Figure 1

(A and B) MRI Cervical spine, sagittal. T1- as well as T2-hypo-intense lesion arising from the posterior element of C4 vertebrae and protruding into spinal canal at this level. Canal is significantly stenosed with obliteration of CSF spaces both above and below C4. Lesion has anatomical as well as signal continuity with bone of posterior element of fourth cervical vertebrae. Spinal cord is critically compressed and shows signal changes in favor of focal myelomalacia extending from lower border of C3 to lower border of C6

Figure 2

(A, B, and C) CT cervical spine, axial and sagittal. Hyperdense broad-based cortical pathology, from ventral surface of the spinous process of C4 and adjoining laminae on either side, protruding into canal to occupy almost all of canal space, to virtually reach up to the dorsal surface of vertebral body itself

Based upon his clinical and imaging features, working diagnosis of cervical compressive myelopathy secondary to fourth cervical vertebrae (posterior element) osteoma in multiple hereditary exostoses was considered. Under general anesthesia and prone position, he underwent C4 laminectomy and complete excision of the lesion. Intraoperatively, spinous processes of C4 was found to be anomalously thickened and irregularly broadened. The lesion was extending on to the ventral aspect of the lamina of the pathological vertebra. Underlying ligamentum flavum and dura was thickened and infiltrated with granulomatous tissue, possibly a longstanding pathological reaction. To release pressure on neural elements, both of these structures were opened, arachnoid was kept intact, the cord was seen pulsating, no CSF leak encountered. It was possible to close dura primarily after releasing the infiltrating overlying granulomatous tissue. The specimen of the pathology is seen in Figure 3. Wound closed in layers, and the patient reversed from anesthesia with no new deficits. The histopathological study confirmed a diagnosis of osteoma based upon findings of dense, compact, and cortical bone with a mature lamellar lesion. He was discharged home on the fourth postop day. The postop CT cervical spine is shown in Figure 4, which confirms complete excision. At discharge, he had symptomatic improvement with a sense of release in the tightness of limbs and subjective improvement of paresthesia. At third month postsurgery, he was able to walk on his own, although with some jerks of residual spasticity. His urinary bladder control was also recovered.

Figure 3

Intraoperative image of osteoma excised en-block. Antero-posterior length of lesion noted is approximately 1.5 cm

Figure 4

(A and B) CT cervical spine, axial and sagittal images revealing post-C4 laminectomy status and complete excision of the lesion with opening up of the cervical canal

DISCUSSION

Osteoid osteoma is a benign bony pathology. Histologically, it has a vascularized nidus located centrally. A capricious volume of neo-osteogenesis further surrounds this nidus. Nidus more than 20 mm are referred to as osteoblastoma, as noted in our patient’s multiple extra-spinal anatomical locations. Clinically, it is seen more often than not in teenagers, with three times more frequency among boys than in girls.[1] Night pains are quite common complaints, which respond well to salicylates.

The most common bone to suffer from this benign pathology is the proximal end of the femur. Clinically, up to 70%–80% of all osteomas are located in long bones; only less than 10% are seen in the spine. Iliac crest and ribs are involved in 40%–60% of cases. Further rare are tarsal and carpal bones, seen to be involved in less than 7% of cases. Osteomas constitute a very rare pathology for spinal tumors. Setti et al.[2] reported a case of a 34-years-old male with C6 pedicle Ivory osteoma. Both before and after this publication, reporting of cervical osteomas (osteomas of axis vertebrae (Odontoid) and sub-axial spine) are rarely seen in the literature. Recently, in 2016, a dynamic component of compression over neural elements were reported.[3] The subaxial cervical spine is again not a common location for osteoma.

Among those seen in the spine, most are located only in the lumbar region, up to seventy percent. Only 20%–25% of all spinal osteomas originate in cervical spine, and very rarely they are encountered in the sacrum or dorsal spine. Therefore, less than 2% of all osteomas are located in the cervical spine. Most of the osteomas in a case of HME do not cause neural compression, as they may have exostoses growth from the outer surface of the laminae. One such rare case example in which two cervical osteomas were noted was published in 1996. In this case, one lesion was originating from the outer surface of C4 lamina, and the symptomatic one was growing inside the canal at C2 lamina, causing significant cord compression.[4]

There are only a few case reports published in the literature for cervical osteoma in a case of multiple hereditary exostoses. At the time of writing this manuscript, and to the best of author’s knowledge, the total number of cervical compressive myelopathy cases secondary to HME published was thirty, including the present case. These all cases are summarised in Table 1. Vertebral levels of osteomas, age, and gender of patients, procedure, and surgery; all are described in detail.

Table 1

Summary of all cervical osteoid osteomas in hereditary multiple exostoses reported so far

S. no.	Year	Author	Age (years) and gender	Duration of symptoms	Vertebral levels	Surgery
1.	1843	Reid[17]	30 M	7 months	C2 (Exact anatomical location not mentioned)	NA
2.	1907	Oschner and Rothstein[5]	23 M	9 years	C2 Lamina	Laminectomy
3.	1910	Obendorff[18]	19 M	3 years	Cervical (Exact level not mentioned)	NA
4.	1951	Slepian and Hamby[14]	33 M	9 months	C6 Posterior arch	Posterior decompression
5.	1964	Rose and Fekete[22]	58 F	Acute Apnoea	C2 Odontoid	Urgent Decompression; Patient did not survive after urgent decompression
6.	1968	Carmel and Cramer[6]	13 F	4 months	C2 Lamina	C1-4 Laminectomy
7.	1970	Chiurco[29]	16 M	3 years	Foramen Magnum	Posterior decompression
8.	1971	Thomas and Andress[15]	21 M	3 years	C6 Lamina	C6 Laminectomy
9.	1971	Vinstein and Franken[13]	14 F	4 months	C1 Lamina	C1 Laminectomy
10.	1974	Madigan et al.[11]	7 F	2 months	C2 Lamina	C2 Laminectomy
11.	1975	Blaauw[20]	39 M	NA	C7 posterior element	NA
12.	1975	Facure et al.[7]	15 M	5 months	C2 Lamina	C2 Laminectomy
13.	1978	Román et al.[24]	37 M	NA	C7-T1 Vertebral Body	NA
14.	1979	Ferrari et al.[8]	23 M	1 year	C2 Posterior element	Posterior Decompression
15.	1980	Singh et al.[19]	29 F	Acute Presentation	C5 Pedicle/ Lamina	Posterior decompression; succumbed after surgery
16.	1980	Palmer and Blum[21] (total three cases)	31 F	2 years	T2 Pedicle	Posterior Decompression
			22 M	6 months	C6 Vertebral Body	C6 laminectomy and hemilaminectomies at C-5 and C-7 with piecemeal removal of the tumor
			14 M	2 years	C7 Lateral Mass	C7 Partial Laminectomy and excision of lesion
17.	1983	Misra et al.[30]	25 M	5 months	C4 Lamina	C4 Laminectomy
18.	1983	Buur and Mørch[27]	33 F	6 months	T4	T2-4 Laminectomy
19.	1989	Tuncer et al.[26]	12 M	2 months	Posterior medial end of left 6th rib indenting T5 Foramina	T5-6 Laminectomy and decompression
20.	1989	Wen et al.[12]	23 F	16 months duration of progressive tetraplegia	C1 Lamina	Urgent C1 laminectomy after acute apnoeic presentation, patient improved after surgery
21.	1989	Tully et al.[23]	12 F	2 year	C5 Vertebral Body	Anterior resection and C4-5-6 fusion
22.	1990	Nunez et al.[9]	15 M	Not mentioned	C2 lamina	C2 Laminectomy
23.	1990	Moriwaka et al.[25]	9 M	3 months	C7-T1 Vertebral Bodies	C6-T2 Laminectomies and C7-T1 Facetectomy with Excision of lesion
24.	1990	Shapiro et al.[10]	11 M	9 months	C2 Lamina	C1-2 Laminectomy
25.	1996	Atabay et al.[4]	17 M	2 months	C2(Symptomatic) and C4 Lamina (Outer surface)	C2 & C4 Laminectomy
26.	1997	Ergün et al.[16]	16 M	1 year	Multiple-level laminae; C3-C6	C3-C6 Laminectomies with Anterior Fixation C4-6 with Plate and screws
27.	2011	Aniba et al.[1]	45 F	2 years	C2 Lamina	C2 Laminectomy
28.	2020	Current report	16 M	2 months	C4 Lamina	C4 Laminectomy

The most common location for cervical osteoma in HME reported so far is C2 Lamina(n = 9),[14567891011] followed by posterior arches of either C1 (n = 2)[1213] or C6 (n = 2).[1415] One of these patients with symptomatic C2 laminar osteoma was a 17-year-old boy with 2-month duration of myelopathy, also had an osteoma arising from external surface of C4 posterior arch.[4] Symptomatic multi-level involvement extending from C3 to C6 has also been reported.[16] In one of the reports, the exact site of pathology in C2 Vertebrae is not mentioned.[17] One report failed to provide the exact details on cervical level from which the osteoma seemed to have originated.[18]

C5 laminar origin of osteoma with its pedicle involvement, lateral mass origin in C7, and posterior arch origin in C7 in single case each, respectively, was seen.[192019-21]

Origin of osteoma from foramen magnum[11] is reported in a single case, with C2 Odontoid involvement in another.[22]

As far as the anterior element of vertebrae is concerned, four separate cases with involvement of vertebral bodies of C5 in one,[23] C6 in another,[21] and C7-T1 in two other cases,[2425] respectively, are reported.

Two separate case reports dealt with the upper thoracic vertebral level osteomas, one in T4, another in T5 secondary to left rib origin.[2627] Both of these cases had compression and extension rostral enough to have caused cervical myelopathy.

Of all the thirty reported cases of HME with cervical compressive myelopathy, twenty were males, and almost fifty percent (n = 14, ten boys and four girls) had presented before completing 18 years of age.

Posterior decompression alone was sufficient enough in all cases, except two reports where anterior fixation was done. One of them was a C5 vertebral body lesion in a 12-year-old girl,[23] and another was after multi-level (C3–C6) posterior decompression in a 16-year-old boy.[16]

In three cases, urgent decompression was needed owing to an acute presentation of apnoea in upper cervical compression secondary to osteoma at C2, C5, and C1, respectively. Two out of these three patients succumbed after urgent surgery.[1922] The survivor was a 23-year-old female who had been suffering from tetraplegia for a 16-month duration and suddenly became apnoeic before taking up for urgent decompression.[12]

Treatment of osteomas differs according to their location and symptomatology. Treatment options range from observation and pain management to surgical excision. Radiofrequency, alcohol, or laser ablation are the less invasive modalities of treatment. Undoubtedly, surgical excision is preferred over other modalities when pathology causes compression over neural structures, as in the present case. After decompression of neural structures is achieved with complete excision of the lesion, spinal fixation is a valid option for preventing spinal instability. This instability is anticipated more when complete excision of lesion demands corpectomy/multiple laminectomies or in lesions that involve facet joints/inter-vertebral joints. In such rare cases, authors preferred to anteriorly fix the spine from C4 to C7 using plate and screw system after the extensive lesion from C3 to C6 was completely excised to achieve adequate neural decompression.[16] In their case, the decision to anteriorly fix the spine appears quite rationale to prevent future kyphosis and instability in a high-risk adolescent male. However, single-level laminectomies without joint involvement can be managed without spinal fixation. This necessitates adequate and periodic follow-ups for monitoring, as is the case in the present report.

Alternative treatment options like radiofrequency ablation (RFA) are utilized only in the absence of neural compression by osteoma. A study published in 2018, which compares CT-guided RFA vs. Open surgical resection (OSR), concluded that RFA is safe and equally effective for the treatment of osteoid osteoma.[28] Patients treated with RFA have shorter hospital stays and experience minimum blood loss with comparable recurrence rates, provided more than 1 mm CSF space between the lesion and Spinal cord/nerve root. The authors further recommended that in the case of the spinal cord or root compression, surgical excision of the lesion is undisputed treatment.

Osteoid osteomas may present either as a solitary lesion or as multiple lesions with a genetic predisposition in the background of HME. Primary prognostic importance in delineating these two entities lies in the fact of the stark difference in recurrence or malignant transformation risk. The risk of recurrences is very high, with the background of HME (up to 25%) in comparison to the solitary lesion (close to 1%). Therefore, spinal osteomas causing cord compression need to be excised completely, both for symptomatic relief and for reducing recurrences.

Pathology of intracanal osteoma in differentials for clinical myelopathy in multiple hereditary exostoses appears straightforward. However, the importance of this clinicopathological fact is being reflected in this rare case. This is not a routine clinical spectrum for neurosurgeons to deal with. Complete surgical excision is invariably the treatment of choice to provide recurrence-free symptomatic improvement. The presence of a very strong positive family history for male inheritance in this case also reflects the significance of hereditary transmission of traits of spinal bony tumors. However, this hereditary transmission may be reflected clinically, with incomplete penetrance of the trait.

CONCLUSION

Cervical intracanal osteoma is a rare pathology to cause a clinical syndrome of compressive myelopathy. When associated with multiple osteomas secondary to hereditary transmission, it further becomes an out of the ordinary clinical picture in neurosurgical practice. Very few cases, only close to thirty, have been reported in the past. This case illustrates one such rare pathology in clinical practice. Authors share all phenotypical, genetic inheritance, imaging, and surgical features they came across for an interesting and rare neurosurgical clinical entity. Complete surgical resection with meticulous techniques of handling delicate compressed neural tissue in high cervical cord gives excellent results in these osteomas and prevents recurrences. Distinct familial male inheritance is a robust genetic behavior of pathology.

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Conflicts of interest

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(A-D) Osseous lesions seen in various parts of musculoskeletal system of the patient. (A) Left calf. (B) Left scapula. (C) Right index finger. (D) Right pelvic bone

(A) X-ray right knee AP view. Radio-opaque sessile lesion with irregular but sharp margins seen originating from proximal end of tibia. (B) X-ray right hip joint AP view. Densely radio-opaque pedunculated lesion with sharp margins originating from anterior superior iliac spine. (C) X-ray left scapula, AP view. Irregular bony growth with mixed radiodensity is appreciated at inferior angle of left scapula