J Gastrointest Surg DOI 10.1007/s11605-015-2779-2

CASE REPORT

Unusual Osseous Metastases from Rectal Adenocarcinoma: A Case Report and Review of the Literature TM Connelly & RP Piggott & RM Waldron & P O’Grady

Received: 12 December 2014 / Accepted: 11 February 2015 # 2015 The Society for Surgery of the Alimentary Tract

Abstract Introduction Rectal adenocarcinoma typically metastasizes to the liver. When osseous spread occurs, it is most commonly detected in the vertebrae and pelvis. Distal osseous spread is unusual and may be the first presentation of the carcinoma. We present a review of the current literature on unusual osseous rectal adenocarcinoma metastases and highlight a case of a scapular lesion as the first presentation of rectal carcinoma from our institution. Materials and Methods A Pubmed search using keywords ‘rectal carcinoma metastases,’ ‘colorectal cancer metastases’ and ‘skeletal metastases’ was performed. Results Twenty-four cases were identified (54 % male, mean age at diagnosis 61±16 years). The most common site was the mandible, followed by the foot. In four cases, the metastasis was the first presentation of the carcinoma. Mean time from resection of the primary tumour to osseous metastases diagnosis of skeletal metastases was 26±17 (SD)months. Mean time from diagnosis of skeletal metastases to death was 3.2 (±2.8)months. Conclusion Rectal adenocarcinoma osseous metastases located distal to the pelvis and/or vertebrae are rare and associated with a poor prognosis. Unusual bony lesions should raise an index of suspicion for distal carcinoma, including rectal carcinoma. Keywords Colorectal carcinoma . Rectal carcinoma . Metastases . Scapula

Introduction Accounting for only 1 % of all osseous metastases, skeletal metastases are relatively rare in colorectal cancer (CRC). Unlike breast, thyroid, bronchial, renal and prostate cancer which commonly metastasise to bone,1 osseous spread is found in less than 25 % of CRC cases. When present, such osseous metastases are typically found in the pelvis and vertebrae.2–6 T. Connelly : R. Piggott : R. Waldron : P. O’Grady (*) Division of Trauma and Orthopaedic Surgery, Mayo General Hospital, Castlebar, County Mayo, Ireland e-mail: [email protected] R. Waldron : P. O’Grady Division of Surgery, Mayo General Hospital, Castlebar, County Mayo, Ireland

Although frequently studied together under the umbrella term ‘colorectal cancer,’ rectal and colon cancer are two distinct entities with different features including the distribution of venous and lymphatic drainage. Of the two, rectal carcinomas communicate more closely with Batson’s venous plexus and, therefore, are more likely of the two to develop metastatic bone disease.3 This communication also results in a connection with the vertebral venous system leading to aberrant metastatic spread. This spread has a primary predilection for the liver and lung. Spread to alternative sites is rare, while the spread to the bone other than the pelvis or vertebrae is very rare. The aim of this work is to describe cases of the aberrant metastatic spread of rectal adenocarcinoma in the form of unusual (non pelvic and non vertebral) osseous metastases reported in the literature to date and highlight a case from our own institution.

Materials and Methods A Pubmed search using the keywords ‘rectal carcinoma metastases,’ ‘colorectal cancer metastases’ and ‘skeletal

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metastases’ was performed. Only English language, full text manuscripts were included. Each manuscript was reviewed for cases of rectal cancer skeletal metastases other than pelvic or vertebral lesions. Only manuscripts inclusive of adequate patient, rectal cancer and skeletal metastases details were included. An isolated case of a patient presenting with a shoulder metastasis from rectal cancer at our institution was identified and a thorough review of patient clinical, radiographic and surgical notes was performed.

Case We present the case of a 53-year-old male who presented to the Orthopaedics department 5 weeks after a fall from a tractor. His only complaint was a left shoulder pain which was disturbing his sleep and limiting his ability to perform overhead activities. On examination, pain was exacerbated by both active and passive movement. Magnetic resonance imaging (MRI) demonstrated a 5×5.6×4 cm destructive lesion involving the blade and spine of the left scapula (Fig. 1). Computed tomography (CT) scans on the thorax, abdomen and pelvis were performed to identify a primary lesion. Lesions were found in the 2nd rib adjacent to but separate from the scapular lesion, the left ilium, left ichial ramus and tuberosity, left inferior pubic ramus and right ilium. Thickening of the rectum was demonstrated (Fig. 2). Perirectal lymph node involvement was noted on positron emission tomography (PET) scan. No pulmonary or hepatic metastases were demonstrated. On direct questioning, the patient admitted to occasional bleeding per rectum with alternating constipation and diarrhoea for a 1-year duration. Family history was negative for colorectal cancer. Colonoscopy demonstrated a circumferential lesion 3.5 cm from the anal verge. Biopsy of the rectal lesion and scapular lesion confirmed poorly differentiated invasive adenocarcinoma primary and metastatic in origin respectively. Staging of a T3N1M1 lesion was completed with an endoanal ultrasound. The lesion extended into the

Fig. 1 CT demonstrating a lytic lesion in the left scapula

Fig. 2 CT demonstrating rectal thickening/rectal carcinoma

perirectal fat with multiple enlarged presacral and perirectal lymph nodes. Neoadjuvant chemo and radiotherapy was given followed by abdominal perineal resection. The osseous metastases were not resected. The patient expired 6 months after diagnosis.

Literature Review Results Patient Demographics and Osseous Metastases Characteristics Twenty-four cases of non-pelvic or vertebral metastases from rectal cancer were identified from the literature (Table 1). One case had confirmed familial adenomatous polyposis.7 Gender was provided for 23 patients. Eleven were female. Mean age at diagnosis was 61±16 (SD)years. The most common site was the head/face, followed by the foot (Fig. 3). In all the cases, the bone metastasis or metastases were painful. In four cases, the metastasis was the first presentation of the carcinoma. One patient presented with concomitant bone and bowel symptoms and the primary tumour and bone metastasis were diagnosed at the same time. In patients who presented with metastases after the discovery of the primary tumour, the mean time from resection of the primary tumour to the diagnosis of skeletal metastases was 26 (±17, SD)months. Mean time from diagnosis of skeletal metastases to death was 3.2 (±2.8, SD) months with the longest survival time of 32 months in a patient with rib and iliac metastases who was alive at the time of print.4 In eight cases, the unusual osseous metastasis or metastases were the only site of metastases (2 sternal, 1 foot, 3 leg, 1 ethmoid and 1 external auditory meatus). Mean age of this patient cohort was 62.9±15.5 (range 30–79). For the five, the stage was not provided. The other three were T4N2, T4N0 and Dukes B1 (at least T2N0). Long-term details were provided for the two. One died in 5 months and the other was alive 29 months after cancer diagnosis. In the 14 who presented with other metastases, mean age was 59±17 years (range

Male

Male

Mandible

Distal phalanx of the left middle finger

Female

Male

Female

Posterior ethmoid and sphenoid sinus/orbit Medial wall of the antrum of the nasal cavity

Mandible

Female

Occipital bone

Male Male

77

Female

Mandible Talus

72

Female Female

Proximal phalnyx 1st, 2nd, 3rd metatarsals, 1st cuneiform and calcaneus Calcaneus

Gender not provided

70

Female

Left zygomatic arch

Greater trochanter of femur

74 79

Male

3rd rib and right Ilium

62

56

56

23 37

48

71

62

58

30 58

Male Male

Sternum Right temporal region

Not provided

Dukes III

Not provided Serosal extension and local lymph node involvement Not provided

T4N2

T3N0

Not provided

Dukes’ IV

Not provided

Not provided Not provided

T3N0

Not provided

Not provided Not provided

Age Stage of rectal cancer (years)

Gender

Unusual osseous rectal metastases

Location of skeletal metastases

Table 1 Treatment of rectal cancer

Unknown

Lung

Liver and lung

Liver+tumour thrombi in IVC Lung

None

Lung

None

Concomitant non-small cell lung cancer and brain metastases Lung, liver andperitoneum

Not provided None

Lung and brain

Not provided

APR

APR and partial hepatectomy

None-autopsy finding Anterior resection

‘Low rectal resection with colostomy’ Surgical details not provided. C/T (FOLFOX 6 cycles followed by 4 cycles of Irinotecanx) ‘Multimodal treatment’ but details not provided Neoadjuvantn C/T (5-FU)+R/T followed by ‘rectal resection’ C/T (oxaliplatin+capecitabine) for pulmonary mets Neoadjuvant R/T and C/T followed by APR. Adjuvant C/T not given due to cardiac ischemia requiring coronary artery bypass surgery

LAR+adjuvant C/T (FU+leucovorin) Not provided None

Right 6th rib and sacrum Patient refused all treatments APR with subsequent bilateral Clavicle, right ischium, pubis, left inguinal LN dissection greater trochanter and 3rd lumbar vertebrae Lung Low anterior resection+adjuvant C/T

Other metastases

C/T (4 intra-arterial infusions of cisplatin into the inferior alveolar artery)+R/T followed by a segmental mandibulotomy with a clear surgical margin+reconstruction C/T (cyclophosphamide, methotrexate, vincristine and 5-FU) Amputation

Femoral neck, subtrochanteric region, including the adjacent part of the gluteus medius and vastus lateralis resected+femoral nailing and cement filling for stablisastion, followed by R/T to the hip None-autopsy finding R/T

Not provided

Partial excision+R/T

Debulking, reconstruction+C/T 2 weeks after surgery R/T (6 Mv photons up to a total dose of 30 Gy in 10 fractions)

‘Palliative excision’ of the metastatic rib tumor due to rib pain+3 cycles of capecitabine C/T+R/T for the iliac bone lesion and therapy. Subsequent intraoperative radio frequency ablation on the right iliac bone lesion with curative intent Palliation only due to ‘advanced disease’ Amputation Amputation

Patient refused all treatments None

Treatment of osseous metastases

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86 61

Male

Female

Female

Male

Male

Female

Female

Tibia

Sternum

External auditory meatus/head of malleolus External auditory meatus

Mandible

Orbit

Mandible

5 years after resection of primary

PET CT and MRI Not provided X-ray X-ray followed by MRI

3rd rib and right Ilium

Left zygomatic arch

Proximal phalnyx

1st, 2nd, 3rd metatarsals, 1st cuneiform and calcaneus Calcaneus MRI, had CT first but lesion not detected initially; was seen on CT second look

Not provided

Clinical observation and biopsy

Right temporal region

Approximately 1 month after diagnosis

Not provided

20 months after resection of primary

14 months after resection of the primary 37 months after resection of primary

Presented with metastasis

Radionucleotide scan and biopsy

Duration between rectal cancer diagnosis and diagnosis of metastases

Sternum

Occipital bone

None

LAR

2 weeks after the completion of R/T, normal tongue movement and correct speech were regained and were maintained despite the progression of

RIP 10 months after resection

RIP 5 month after diagnosis

RIP 3 months after finger metastases

Disease-free at 32 months after diagnosis of bone metastases RIP 2 months after skull metastases

No details on long-term outcome provided RIP 3 months after facial metastases

Outcome

Marruecos et al.19

Ellington et al.14

Sworn et al.11

Sur et al.26

Danikas et al.17

Choi et al.22

Bacon et al.5

Choi et al.4

Reference

R/T to cheek due to rapid growth

R/T

Debulking

No details provided

R/T + ’palliative C/T’ (capecitabine+zoledronic acid) C/T (FU+FA) initially; after progression of sternal lesion, 2nd line C/T was started (Capecitabine) After 1 year, oxaliplatine+R/T was given to 2 new vertebral metastases None

R/T, ‘curative resection not possible because of liver metastases.’

‘Palliative’ APR APR

Treatment of osseous metastases

Treatment of rectal cancer

Surgery postponed for C/T when metastases were discovered. No further details Liver and left 3rd, 8th and right 12th ‘Due to extent of mets’ no surgery ribs provided Eye, lumbar vertebrae andbreast APR including posterior vaginal wall. (Patient refused neoadjuvant and defaulted on adjuvant treatment) Right parotid LAR; no adjuvant treatment given ‘due to age’

None

Liver, omentum and ribs

None at diagnosis; sacral iliac joint metastases discovered after sternum

None at the time of diagnosis of tibial met; liver mets discovered 6 months later None

Diagnosis of osseous metastases

T3N0

Not provided

Not provided

Not provided

Not provided

T4N0

Dukes B1

Not provided

Other metastases

Location of skeletal metastases

70

32

70

68

78

67

Male

Tibia

Age Stage of rectal cancer (years)

Gender

Location of skeletal metastases

Table 1 (continued)

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3 years after resection of primary Presented with concomittant signs and symptoms of both the primary and metastasis 1 year after resection of primary

Metastasis was the first presentation. 3 weeks after rectal cancer diagnosis

X-ray demonstrated a mixed osteoblastic-osteolytic mass. PET was used to futher clarify Autopsy finding Initial X-ray did not reveal any lesion. X-ray 5 months later demonstrated a destructive lesion CT whole-body gallium scintigraphy Clinical exam Not provided Clinical exam and biopsy X-ray followed by bone scan CT followed by radionucleotide scan

Autopsy finding Clinical exam and biopsy Clinical exam and biopsy MRI CT

Greater trochanter of femur

Talus

Mandible

Mandible

Distal phalanx of the left middle finger Tibia

Tibia

Sternum

External auditory meatus/head of malleolus External auditory meatus

Mandible

Orbit

Mandible

Creedon et al.10 Chalkidou et al.12

No long-term follow-up was provided. Pain relief after R/T; ‘Stable disease’ 19 months after R/T and C/T for metastasis After initial C/T, the sternal metastasis increased in size. At 18 months after 2nd line C/T and R/T to vertebrae, an increase in the sternal mass was seen. Long-term details not provided RIP 10 days after presentation

49 months after resection of primary

10 months after resection of primary

Metastasis was the first presentation.

Metastasis was first presentation

3 years after resection of primary

RIP before completion of radiotherapy

RIP during radiotherapy for metastases

RIP 3 months after diagnosis

Not provided

Kerin et al.25

Patient was ‘free of cancer’ >3 years after the segmental mandibulectomy. RIP during admission for treatment of mandibular metastases RIP 4 months after finger amputation

Hsu et al.15

Hisham et al.24

Coad et al.27

Carr et al.8

Sadek et al.60

Scuderi et al.20

Moffatt et al.9

Soda et al.23

RIP 8 months after foot metastasis

5 years after resection of primary 26 months after resection of primary

Johnson et al.2

RIP 3 months after metastases

Ooya et al. 7

Nijs et al.13

Conill et al.16

Tanaka et al.18

Reference

Not provided

30 months after resection of primary

34 months after resection of the primary

visceral metastases. Long-term outcome was not provided. At 3 months postoperatively, there was no improvement in vision and no change in the tumor size. Long-term outcome was not provided. Lung metastases progressed after C/T. Long-term follow-up was not provided. Not provided

Outcome

APR abdominal perineal resection, R/T radiotherapy, C/T chemotherapy, LAR low anterior resection, LN lymph nodes, MRI magnetic resonance imaging, CT computed tomography, FU flurouracil

Mandible

CT

Medial wall of the antrum of the nasal cavity

1 year after resection of the primary

CT followed by MRI

Posterior ethmoid and sphenoid sinus/orbit

Duration between rectal cancer diagnosis and diagnosis of metastases

Diagnosis of osseous metastases

Location of skeletal metastases

Table 1 (continued)

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Fig. 3 PET scan demonstrating increased uptake in the right scapula, 2nd rib, left ichial ramus and tuberosity, left inferior pubic ramus and right ilium

32–86). Three had T3N0 disease, one was classified as Dukes II, and one was Dukes IV. Stage was not provided for the remaining 8. The most common sites of spread were the lung (n=7), liver (n=5), vertebrae (n=2), brain (n=2) and parotids (n=1).

Diagnosis and Treatment Four metastases (external auditory meatus, mandible, tibia and right temporal region) did not undergo imaging and were diagnosed by clinical exam and biopsy.5,8–10 X-ray was the sole radiographic modality used for diagnosis in two cases of foot metastases.2,11 In Johnson’s case, no talar lesion was evident on initial X-ray. However, repeat X-ray after 5 months revealed a lesion.2 Bone scan, MRI and PET were used to further clarify a tibial, foot and greater trochanteric lesion, respectively.12–14 CT scan alone was used in two head lesions, Hsu’s cheek and Conill’s nasal cavity metastases.15,16 Danikas and Tanaks utilised CT and MRI for the investigation of skull lesions.17,18 Interestingly, in one case of an occipital bone lesion, initial CT was reported as negative for lesions. A follow-up MRI demonstrated the metastasis. On second look, the lesion was visible on CT.19 Scuderi used bone scan as a modality to identify other spread and found that, in addition to the sternal lesion seen on CT, sacroiliac lesions were also present.20 Bone and PET scans were similarly used to identify

other lesions in three other cases, one with a sternal metastasis, one with a rib lesion and one21 with a mandibular lesion.4,22,23 Four patients underwent radiotherapy as the only treatment for unusual bone metastasis in a mandible, orbit, occipital bone and tibia.19,24 Two died during treatment (mandible and orbit).15,19,24 No follow-up was provided for 1 (tibia).10 The patient with the occipital lesion affecting tongue movement experienced a full return of tongue movement and normal speech despite progression of other lesions (lung, liver and peritoneum). Long-term outcome was not given.19 Two underwent only chemotherapy, a zygomatic arch and mandible. Both died during treatment.9,17 One underwent both radio and chemotherapy, a tibial lesion. Nineteen months after treatment, the lesion was still present on X-ray and showing uptake on bone scan. However, he was pain-free.12 Nine patients underwent surgical treatment of their bone metastasis. Two fingers were amputated. Both patients expired within 4 months of resection.25,26 Of the 2 foot lesions that underwent resection and debulking (with chemotherapy), both expired within 10 months of surgery.11,14 Choi reported the excision of an affected rib followed by chemoradiotherapy. The treatment was considered to be a palliative, pain relieving measure. However, 32 months after resection, no disease was found on CT, MRI or bone scan.22 Another favourable report of a resection was that of a mandibulectomy which was preceded by chemoradiotherapy. The patient was ‘cancer free’ at 3 years.23 Nijs et al. report the case of a hip lesion that was resected with all macroscopically surrounded tissue. Microscopic disease was detected and radiotherapy to the hip was given. Five months after resection, a PET scan demonstrated hot spots in both the shoulders, pelvis and spine. The left hip showed no pathological FDG uptake. Long-term details were not however provided. Another reports of partial excision in a mandible (without chemo or radiotherapy)27 did not show improvement and the patient passed away 5 months later. In Tanaka’s partial excision of a lesion involving the posterior ethmoid, sphenoid sinus and orbit followed by radiotherapy, the patient’s vision did not improve; however, there was no increase in the size of the metastasis after 3 months. Longterm outcome was not provided.18

Discussion The typical locations of skeletal metastases from rectal cancer are the vertebrae and pelvis.28 First described by Curling during autopsy in a patient with rectal cancer and a concomitant radial lesion in 1870, the phenomenon of aberrant skeletal metastasis is relatively rare.29 Skeletal metastases with sparing of the intraabdominal organs in rectal cancer are rarer still. A retrospective review of rectal cancer patients treated over 25 years performed by Kanathan et al. revealed a 1 %

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incidence of such behaviour in their 137 rectal cancer patients with skeletal metastases.28 Tumours typically spread by direct invasion, across body cavities, via lymphatics or through the venous system.30,31 As a result of these patterns, the rate of abdominal metastases are higher in colon cancer patients while rectal cancer patients more often have extra abdominal metastases.32 Rectal tumours can metastasise across the peritoneal cavity resulting in ovarian metastases,33,34 via lymphatics, resulting in local, paraaortic and even inguinal lymph node involvement35 and through the venous system with subsequent liver, splenic and pulmonary deposits.36 The perirectal, superficial perineal accessory lymph pathway and presacral chains are routes of lymphatic spread. The perirectal lymph nodes are located along the vascular trunk. The middle and inferior haemorrhoidal veins which drain the rectum then drain into the inferior vena cava (IVC) and ascending haematological spread. The most studied intermediary in the spread of rectal cancer is Batson’s plexus. The rectum lies adjacent to and is drained by this sacral venous plexus allowing for spread which is most commonly to the pelvis and spine. Metastases bypass the portal and caval venous systems in this manner allowing seeding into the vertebral column and sacrum. The sacral venous plexus is rich with anastomoses and valve formation distally is variable within the system. All veins, however, permit blood flow towards the plexus.37 Demonstrated by Batson’s early contrast injection cadaveric and murine studies, the pathway of venous tumour deposition is via the plexus to the common iliac and proximally to the IVC or bypassing the vena cava and instead taking a path through the paravertebral vessels to the intercostal Fig. 4 The anatomical locations of the 24 unusual osseous rectal metastases described in the current literature

vessels and skull and/or the femur. Although in Batson’s studies, spread was directly proportional to the amount of contrast material injected, this likely does not correlate with tumour spread as even tumours limited to the submucosa can follow any of these patterns.38 Thus, spread may be more influenced by host factors and tumour factors, including chemotactic, vascular permeability and homing cytokine profiles. Batson also demonstrated that the epidural and vertebral vein networks have an extensive system of anastomosis with the veins of the thoracoabdominal cavity at each spinal segment. This is a low pressure system with few veins except in minor connecting channels. With valsalva, pressure is increased significantly to force blood into the vertebral system bypassing the IVC.37 This is likely the pathway that was involved in the pathogenesis in the patient described in our case study. Distant spread without organ involvement as demonstrated in our case may result from a combination of host immune response, vascular permeability chemotactic factors and other cell signaling mechanisms.2 This potential stimulatory interaction between the tumour and host cells has been coined the ‘seed and soil’ hypothesis.39 The venous supply to the scapula includes a network including the dorsal scapular vein which communicated with the intercostal veins and is likely the path of spread in our case. Reported cases of unusual metastases sites in rectal cancer include the thyroid,40,41 adrenal gland,42–44 skin (including face and upper limbs),45,46 gingiva,47 heart,48,49 biliary tract,50,51 pituitary gland52 and breast.53–55 The above study highlights unusual skeletal locations of documented rectal metastases (Fig. 4). Some sites such as the hands and feet are

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particularly unexpected. Hand and foot metastases are typically not rectal in origin. This was demonstrated in a study by Kerin et al. who documented 23 cases of bony metastases to the carpal bones and phalanges, only one of which was rectal in origin. Interestingly, similar to our case study, in the majority of these cases, the hand lesion was the first presentation of the carcinoma.25 Some interesting findings from the current work include the observation that every unusual osseous metastasis presented with pain, confirming that all patients presenting with unusual bone pain warrant a thorough work up. In all the cases where details on X-ray finds were given, lesions were clearly osteolytic. The X-ray of the trochanteric lesion revealed both osteoblastic and osteoclastic features prompting further investigation.13 CT and MRI are useful and recommended to further investigate the lesions and evaluate for invasion into surrounding structures, particularly in the head/skull. Due to the occult nature of metastases and the observation of several additional lesions that were only found on PET imaging or bone scan highlighted above, we suggest PET scan for all these patients. Although radio and chemotherapy had varied results, a reduction in pain following radiotherapy was noted in several cases. Surgical excision was associated with varying results from death after 5 months of finger amputation to what was reported as a patient being ‘disease free’ at 32 months, which is the best outcome reported in all the cases of unusual osseous metastases. The presence of metastases is directly correlated with poor prognosis; however, the majority of studies focus on the more common liver, lung and brain mets.56,57 The median survival of patients with bony metastases ranges from 4 to 7 months.12,58 But this has been reported as long as 13 years.28 In the Bonnheim’s 10-year study of 1,406 colorectal cancer cases, 19 patients with isolated osseous metastases had a median survival of 10 months vs 47 patients with bone and other distant metastases who had a median survival of 6 months.59 Limitations This study is limited by the heterogeneous nature of manuscripts from which the cases were recorded. Thus, this study provides an overview. Tumour stage was unavailable for the majority of cases. There is insufficient data provided to compare patients who had only unusual bony metastases without lung, liver or vertebral metastases with patients who had spread to both sites. This is an interesting cohort, those with spread that ‘skips’ the typical route. Similarly, outcomes data was missing on a large number of patients. The cases reported are heterogeneous in regard to patient factors and comorbidities which would influence choice of treatment. Importantly, patient general physical condition was only mentioned in two manuscripts). It should also be noted that, due to the wide time frame in which these papers were written (from 1949 to 2013),

standard diagnositic modalities and treatment regimens varied. Additionally, treatment is often guided by surgeon preference, and in the case of unusual osseous metastases, there is little literature to guide surgical decision making. Despite these limitations, this work provides a concise overview of the aberrant rectal skeletal metastases documented to date. This data should be used to raise awareness in patients presenting with unusual bone pain, particularly without a history of trauma. We did not highlight the other primary and secondary causes of malignancy in bone. These are numerous and beyond the scope of this work but should be included in the differential diagnosis of these patients. Our work was limited to rectal adenocarcinoma only for clarity. Skeletal metastases in squamous cell, signet ring and other rectal cancers may differ.

Conclusion Aberrant skeletal metastases from rectal adenocarcinoma are a relatively rare entity. The cases in which no evidence of visceral (lung and liver) spread is found are particularly rare. Pathophysiology likely involves an interplay between the valveless sacral plexus drainage of the rectum leading to a connection with the vertebral venous system and yet unknown host and tumour factors. These lesions are most commonly located in the mandible and feet. Overall, prognosis in these cases is poor. A high index of suspicion for an underlying malignancy should be held in unusual cases of bone pain.

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