Primary cutaneous osteosarcoma of the scalp: a case report and review of the literature
Abstract: We report on an 84-year-old man with a solitary, nodular lesion on the scalp. The patient had been previously sub- mitted to electrodessications of the scalp due to multiple solar keratoses.
Histopathologically, the lesion showed features of a high-grade con- ventional osteoblastic osteosarcoma involving the dermis. Computed tomography showed no involvement of the underlying bone tissues.
Clinical examination and extensive total body radiologic workup revealed absence of bone lesions in any body site, thus suggesting a final diagnosis of primary cutaneous extraskeletal osteosarcoma. The clinico-pathological features of the case are discussed in light of the rare cases previously described in the literature.
Massi D, Franchi A, Leoncini G, Maio V, Dini M. Primary cutaneous osteosarcoma of the scalp: a case report and review of the literature.
J Cutan Pathol 2007; 34: 61–64.# Blackwell Munksgaard 2006.
Daniela Massi1, Alessandro Franchi1, Giuseppe Leoncini1, Vincenza Maio1and Mario Dini2
1Department of Human Pathology and Oncology and
2Department of Plastic Surgery, University of Florence, Florence, Italy
Prof Daniela Massi, Dipartimento di Patologia Umana ed Oncologia, Universita` degli Studi di Firenze, Viale G.B. Morgagni 85, I-50134 Firenze, Italy
Tel:þ39 055 4478137 Fax:þ39 055 4379868 e-mail: daniela.massi@unifi.it
Accepted for publication November 22, 2005
Extraskeletal osteosarcoma is a rare malignant neo- plasm accounting for approximately 2–4% of all osteosarcomas.1 By definition, the tumor does not arise from bone but may secondarily involve the peri- osteum, cortex, or medullary canal. It typically arises in male patients during mid and late adulthood in the deep soft tissues of the thigh.1–3 Other less frequent sites include the buttock, shoulder, trunk, and retro- peritoneum.1 The majority of extraskeletal osteosar- comas develop de novo, but up to 10% of cases have been associated with previous radiation or trauma.2 Only 10% of extraskeletal osteosarcoma are super- ficially located, and the skin may be involved in the setting of widespread metastatic dissemination from a skeletal or extraskeletal osteosarcoma.4–9 The occur- rence of an extraskeletal osteosarcoma arising primar- ily in the skin is an exceedingly rare finding.
We herein describe an 84-year-old patient develop- ing a primary cutaneous extraskeletal osteosarcoma on the scalp and discuss its clinico-pathological features in view of the cases previously described in the literature.
Case report
An 84-year-old man presented with a solitary, rapidly growing, exophytic, nodular lesion located
on the scalp (vertex region). Physical examination revealed that the reddish cutaneous nodule had firm consistency and measured 2 cm in diameter. The lesion had been present for 3 months. The patient had been previously submitted to electrodessications of the scalp for multiple actinic keratoses. Medical history was otherwise unremarkable. Computed tomography showed that the lesion extended in soft tissues to the level of the fascia but did not involve the underlying bone. The tumor was excised with a clinical diagnosis of cutaneous carcinoma.
Histopathological examination showed an atrophic epidermis overlying a dermal proliferation of atypical cells embedded within abundant extra- cellular matrix (Fig. 1). Neoplastic cells were a mix- ture of predominantly spindle and epithelioid cells often exhibiting pronounced nuclear atypia and grew in large, cohesive sheets. Scattered osteoclast- like giant cells were distributed within spindle-cell areas (Fig. 2). High mitotic activity, with numerous atypical mitoses, was noted in the superficial and deep portions of the lesion (Fig. 3). The osteoblastic nature of tumor cells was recognized by their close apposition to trabeculae of tumor bone or by their entrapment in lacelike osteoid deposits. The extra- cellular matrix was recognized as a dense, fibrillar eosinophilic substance deposited between groups of
J Cutan Pathol 2007: 34: 61–64 doi: 10.1111/j.1600-0560.2006.00562.x Blackwell Munksgaard. Printed in Singapore
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cells. More advanced signs of mineralization produ- cing clearly recognizable trabeculae of woven tumor bone were also noted. The tumor bone trabeculae were haphazardly arranged, had irregular borders, and merged gradually with areas of less mature osteoid. Areas of necrosis were not observed.
Immunohistochemical analysis showed positivity of tumor cells for vimentin and osteonectin, whereas S-100 protein and cytokeratins were negative. Upon histopathological examination, clinical examination and extensive total body radiologic workup were performed. No other bone lesions were demon- strated, thus suggesting a final diagnosis of primary cutaneous high-grade conventional osteoblastic osteosarcoma. The patient did not receive adjuvant therapy and is alive and well with no recurrences after 6 months’ follow up.
Discussion
Mature bone may be found in the skin in the various forms of osteoma cutis, but true neoplasms with differentiation toward bone are exceedingly rare in the skin. Cutaneous ossification may occur as a primary form (osteoma cutis), where there is an absence of a pre-existing or associated lesion, and a secondary type (metaplastic ossification), where the process of ossification develops in association with or secondary to inflammatory (scleroderma, dermatomyostis, and chronic venous insufficiency), traumatic (injection sites, scars), or neoplastic processes (melanocytic nevi, basal cell carcinomas, pilomatrixomas, chondroid syringomas, dermatofi- bromas, carcinomas, and desmoplastic melanomas).
In these cases, small spicules or large masses of bone tissues are seen in the dermis and/or subcutis and usually develop by membranous ossification without the presence of a cartilage precursor. In the current case, cellular atypia, along with a high mitotic activity with atypical mitoses, and the dis- ordered architectural pattern strongly suggested a malignant neoplastic process, either primary or metastatic.
Osteosarcomatous components have been described in malignant melanoma10 as well as, rela- tively more commonly, in the setting of so-called metaplastic or biphasic sarcomatoid carcinomas or carcinosarcomas. In such metaplastic carcinomas, both malignant epithelial and mesenchymal ele- ments, including signs of osteoblastic differentiation, are simultaneously present.11 Although the chance of sampling error always has too be taken into care- ful consideration, in our case no signs of epithelial component were demonstrated in serial deeper sec- tions, thus ruling out the possible diagnosis of a biphasic carcinosarcoma.
Fig. 1. Scanning magnification shows an atrophic epidermis over- lying a dermal proliferation of atypical cells embedded within abundant extracellular matrix.
Fig. 2. Neoplastic cells were a mixture of predominantly spindle and epithelioid cells often exhibiting pronounced nuclear atypia and grew in large, cohesive sheets. Scattered osteoclast-like giant cells were distributed within spindle-cell areas.
Fig. 3. A high mitotic activity, with numerous atypical mitoses, was noted in the superficial and deep portions of the lesion. Tumor cells merged gradually with areas of less mature osteoid.
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Table 1. Review of reported cases of primary cutaneous extraskeletal osteosarcomas
Author Cases
Age
(years)/sex Site Size Therapy Follow up Status Notes
Drut (1975) 1 case 70/female Right thigh – – – – Arisen in old
burn scar
Fletcher (1987) 2 cases – Lower leg – – – – Arisen in chronic
tropical ulcers
Chung and Enzinger (1987) 2 cases – – – – – – Tumors confined to
the subcutis or dermis
Reyes (1989) 1 case 62/male Temporoparietal
region
5 3 cm Surgery No recurrences DOC, 7 months Previous radiotherapy
for epiauricular basosquamous carcinoma
Kuo (1992) 1 case 51/female Popliteal region 3 3 cm Surgeryþ chemotherapy þ radiotherapy
– –
Kobos (1995) 1 case 78/male Shoulder 1 1 cm Surgery Local recurrence
after 9 months
DOC, 15 months
Kircik (1995) 1 case 83/female Frontal and
parietal region
– Surgeryþ radiotherapy Lung metastases – Previous trauma
Pillay (2000) 1 case 56/female Scalp 8 8 cm Surgeryþ chemotherapy Metastases after
6 months
–
Santos-Juanes (2004) 1 case 96/female Right temple 4 3 cm Surgery No recurrences DOC, 24 months Arisen under a
previously electrodessicated actinic keratosis
Massi (2006) 1 case 84/male Scalp 2 2 cm Surgery No recurrences Alive, NED, 6 months Arisen on a previously
electrodessicated scalp due to multiple actini keratoses DOC, dead of other causes; NED, no evidence of disease.
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In the current case, the overall cyto-architectural picture was in line with a malignant tumor involving the dermis and composed of tumor cell having the ability to produce osteoid and mature bone; thus, the hypothesis of an osteoblastic osteosarcoma, either primary or metastatic, was considered.
Given the patient’s age, the possibility of cutaneous metastases from osteosarcoma arising in association with pre-existing bone diseases, such as Paget’s dis- ease, fibrous dysplasia, chronic osteomyelitis, bone infarct, or postirradiation, was intriguing. Indeed, skin metastases from skeletal and extraskeletal osteo- sarcomas have been seldom reported. However, in the context of the clinical setting (absence of under- lying or distant bone or soft tissue lesions), we inter- preted the lesion as a primary cutaneous extraskeletal osteosarcoma.
Review of the literature showed that skin as a primary site is a rare event (Table 1).12–19There are some hints to extraskeletal osteosarcomas confined to the dermis and subcutaneous tissue in two of 88 cases reported by Chung and Enzinger,2 in two cases reported by Fletcher13 in association with chronic tropical ulcers, but the first case of primary cutaneous osteosarcomas with complete clinico- pathological data was described by Kuo in 1992.15 Interestingly, there is one report suggesting a possi- ble association with burn scars,12 previous radia- tion,14 and electrodessication of actinic keratoses,19 as in our case. However, the causal relationship between these conditions and the development of the tumor has still to be demonstrated with cer- tainty. The scalp seems to be a common site for occurrence, and all patients are in their early or late adulthood. The prognosis of soft tissue extra- skeletal osteosarcoma is generally poor, with patients experiencing local recurrences often followed by metastatic dissemination. Concerning cutaneous osteosarcoma, the number of cases described so far is too low to draw definitive conclusions, although it is conceivable that the small, more superficial sarco- mas may behave better than their deeper counterparts.
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