Month's Case: Metastatic Lung cancer mimicking Osteomyelitis of Thumb

Introduction

Acrometastasis to the hands are not commons and often misdiagnoses. Only 0,1 % of all metastatic have osseous involvement¹. Despite the rarity of the lesion, awareness of its possibility  is important to prevent this misdiagnosis of infection and a delay in proper treatment². The most common location is the distal phalanx and the primary side the lung. We describe an 81-year-old patient who presents an erythema and swelling in distal right thumb phalanx, whose final diagnosis was an acrometastasis of primary lung neoplasm.

Case Report

An 81-year-old right hand man was referred to our orthopaedic unit following an one week history of painful and inflammation at right thumb initially treated with antibiotics for suspected whitlow that not evolved correctly. His past medical history included Alzheimer disease, benign prostatic hyperplasia, obstructive pulmonary disease and an undifferentiated lung neoplasm diagnosed five months previously. The tumour was initially evaluated as T2N2M0 and the patient was not treated due to family refusal for aggressive treatments because of the patient's clinical situation.

On physical examination the patient was no febrile with stable status. He present an intensive painful swelling, redness with increased temperature completing a fluctuating wound in the volar aspect of the distal right thumb phalanx. Active interphalangeal flexion was decreased for pain. Radiographs showed an osteolytic process without reactive new bone formation involving the distal epiphysis. There was no evidence of pathologic fracture (fig 1-A). It also identified a soft tissue component but no periostal reaction. Blood tests not revealed an inflammatory syndrome. The suspected diagnosis was acute osteomyelitis of the right thumb distal phalanx.

Emergency abscess opening is necessary to obtain samples of exudate, it was dense but not smelly. Because of the poor outcome we decided initial hospitalization for intravenous antibiotic therapy with levofloxacin, rifampin, and symptomatic control of pain.

The lesion of the distal thumb had no good evolve, the exudation is very low but after 48 hours of emergency drainage it maintained septic appearance and showed a friable granulation tissue and soft protruding in the primary incision area (figure 1-B). The bacterial cultures were sterile. After five days, the tissue reagent has grown and acquired a greyish appearance. We decided amputation.

Amputation was performed with a fish mouth incision and resection of the proximal phalanx. A piece of 4x3,5 cm was reviewed in pathologic examination. Histological test revealed an squamous metastasis of the primary lung tumour (Fig 2A y B). The postoperative course was uneventful maintain a prophylactic antibiotic who was removed early and he has discharged after 72 hours. The patient was review after ten days with good evolve. He remained asymptomatic with good healing. Six months after surgery, he died due to a pulmonary complication.

Discussion

The distal digital metastases are uncommon. The frequency varies according to the series but is generally closer to 0.1% in the hands¹. Lookingbill et al³ identify only 9 of 7319  in her retrospective study but concludes that the effect may be even smaller if one takes into account those that were not bone disease. In the Cohen’s revision⁴ of distal metastasis its represent one of the initial signs of internal malignancy unknown in half the patients, but other locations are the first sign of less than 1%.

The most common location of distal acrometastasis are the fingers in hand. Topographic distribution of 62% for the phalanges, shows that most often location of this are the distal phalanx and the lowest frequency in the middle phalanx, where there are so rare⁵. The finger most commonly affected is the thumb.

Simple Radiographs shows an osteolytic disease, except in a few cases of prostatic osteoblastic acrometastasis. Physical examination is variable but typically is very painful. The distal phalanx appears red, swollen, painful and fluctuating. Deforming the finger ends showing a so-called "false Acropachy"⁶. At this point it is necessary to make differential diagnosis with conditions such as paronychia, osteomyelitis², rheumatoid arthritis, gouty arthritis, algodistrophy⁹ or tenosynovitis. Biopsy under local anaesthesia can provide the definitive diagnosis in superficial lesions. As in our case the initial confusion of acrometastasis as an infectious disease can delay diagnosis and lead to an initial mishandling of this.

The most frequent primary tumour side is the lung (41%), gastric (11 %) and then the breast. Other less common primary tumours are the gastrointestinal tract, uterus, testis or secondary cases have been described in melanoma, chondrosarcoma, or cancers of the oral cavity. When the source of the primary tumor is the urogenital tract or the colon tend to lead to lower limb acrometastasis⁴. All tumours can produce an acrometastasis⁸ but the chief histologist type is the epidermoid.

The way that the distal spread happens is no well know. Factors like traumatism, hormonal and immune changes, the temperature gradient and the inherent properties in the cell that spears are certainly involved¹⁰. When metastatic disease appears indicates an ominous prognosis, most patients survived less than six months. Improved survival has been published since the diagnosis for certain types of tumours, especially the kidney, with survival up to 15 months¹¹. Advances in the diagnosis and treatment of primary tumours are the cornerstone of this improvement.

The treatment of this disease may include chemotherapy, excision, amputation, or ray resection with curettage and filling of the cavity for small lesions in terms of overall patient. It should be considered as a palliative for symptomatic relief, extended survival, maintaining quality of life, and preservation of maximal hand function.

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AUT ORES: ANTONIO TORRES CAMPOS, MIGUEL RANERA GARCÍA (HCU LOZANO BLESA ZARAGOZA)