What is neoplastic disease?
The word neoplasm, meaning new growth in Greek, refers to any abnormal growth, whether malignant or benign. Neoplastic disease refers to both malignant and benign growths.
All types of cancer fall into the category of malignant neoplastic diseases. Benign neoplastic diseases, or benign growths, can also negatively impact human health and leave skeletal evidence similar to that of malignant growths. It is important to analyze skeletal evidence for signs of both benign and malignant disease to better understand the dynamics of neoplastic disease in the past.
A benign growth is generally a slow growing, tumor localized to one area of the body. Some benign tumors may become malignant, such as giant-cell tumors, ovarian teratomas, meningiomas, and osteochondromas.
If the tumor is consistently growing, made up of poorly differentiated tissue, and has the potential to involve other parts of the body, it is considered malignant. Malignant growths, commonly known as cancer, are often defined by the rapid growth of abnormal cells that:
1) are capable of destroying surrounding normal tissue
2) do not adhere to normal growth-regulating mechanisms
3) can establish new growths in other regions of the body through vascular channels.
Two types of malignant tumors that involve the bone are sarcomas and carcinomas. Carcinomas occur in epithelial tissues, whereas sarcomas manifest in tissues that originate in the mesodermal layer, such as bone or muscle tissue. Sarcomas may metastasize, but metastasis is occurs more commonly in carcinomas.
PRIMARY CANCER, SECONDARY CANCER AND METASTASIS
Primary cancer refers to the first malignant tumor to form and its original location. If the primary cancer spreads, or metastasizes, the resulting cancer is called the secondary cancer. Most primary malignant tumours begin in the soft tissue and are therefore extremely difficult, and sometimes impossible, to detect in the skeleton through visual examination. Advances in biological analysis, however, may reveal new techniques for the identification of genetic or cellular mutations, cancer biomarkers, and immuno-assays.
malignant neoplastic disease
currently detectable in the skeleton
Many cancers manifest only in soft tissues. Consequently, it is sometimes difficult, or impossible, to detect the presence of cancer in skeletal human remains. Mummified remains can provide evidence of other cancers due to the preservation of soft tissue. The following are descriptions of cancers primarily identified in skeletal remains.
Metastasis is a secondary effect, a result of the vascular spread of cancerous cells to another region of the body from a primary lesion. Metastasis to the bone is much more common than the manifestation of primary bone tumours. Recent studies indicate that 85% of untreated individuals with carcinomas demonstrate skeletal lesions (Dorfman and Czerniak 1998). The soft tissue organs generally responsible for metastasis are malignant tumors of the breast, lung, kidney, rectum, pancreas, stomach, prostate, and ovaries (Abrams et al. 1950).
Metastatic lesions on the skeleton can be osteolytic (destruction of bone), osteoblastic (bone formation), or mixed. However, lesions from the spread of cancer to the bone are predominantly destructive, with the exception of metastases from prostate cancer, which is primarily osteoblastic in nature.
Multiple myeloma, also known as ‘plasma cell myeloma’ and ‘myelomatosis,’ is the malignant proliferation of plasma cells in bone marrow (Steinbock 1976). This condition occurs in bones containing haematopoietic marrow in adults (e.g. vertebrae, ribs, the skull and pelvis) and, in advanced stages, can be found in isolated parts of the femora, humeri, scapulae and clavicles. Multiple myeloma generally presents as small, sharply demarcated lesions that perforate the inner and outer tables of the skull, and include scalloped margins. Pathological fractures and signs of anemia are both associated with the presence of the disease in skeletal remains.
In a visual examination of a skeleton, multiple myeloma and metastatic carcinoma can be easily confused. Both malignancies produce similar lesions and are not easily distinguishable. Several authors have published papers on the considerations of differential diagnoses between these two neoplastic diseases (Marks and Hamilton 2007, Rothschild et al. 1998, Strouhal 1993). [For further reference, see: Steinbock 1976: 374-384, Ortner 2003: 376-382, Brothwell 2008: 275-276, Aufderheide & Rodriguez-Martin 1998: 371-392]
An osteosarcoma is a primary malignant tumour of the bone that originates in the metaphyses (the growth plates at the ends of long bones) and tends to manifest during the most rapid growth periods, often between 10 and 25 years of age. However, a small percentage of cases occur after the age of 50 and are generally associated with pre-existing Paget’s disease. Eighty percent of osteosarcomas are found in the long bones of individuals under 30 years of age, and in small flat bones of individuals over the age of 40. The majority of osteosarcomas manifest in the distal portion of the femur and average 10 x 3 cm in size, although larger lesions in size have been recorded in more advanced cases.
The formation of an osteosarcoma begins with the destruction of the inner trabecular (spongy) bone followed by destruction of the outer cortical bone. Follow bone destruction, new bone is generally deposited in layers along vascular channels, giving the bone tumor a “sunburst” appearance. The new bone can also be deposited in layers parallel to the bone’s surface giving it an “onion peel” appearance, although this is not as common.
Alternative, or additional, considerations when conducting a differential diagnosis for a neoplasm resembling an osteosarcoma may include: chondrosarcoma, Ewing’s sarcoma, fibrosarcoma, pareosteal osteosarcoma, fibrous dysplasia and callus following a fracture. These conditions may appear very similar in skeletal remains. [For further reference, see: Steinbock 1976: 362-71, Ortner 2003: 524-25, Brothwell 2008: 276-77, Aufderheide & Rodriguez-Martin 1998: 377-79]
Chondrosarcoma, like osteosarcoma, is a primary malignant tumor that occurs most commonly in the metaphyses of long bones. The tumor either manifests directly as a malignancy, or can transform from a benign neoplasm of the cartilage into a malignant neoplasm. The chondrosarcoma destroys the trabecular bone and erodes the endosteum, creating a scalloped appearance of the bone’s surface. More advanced stages of the tumor produce large nodular masses of new bone developing on the surface of the bone, often producing an organized pattern of trabecular bone in the center of the mass.
Although chondrosarcomas and osteosarcomas can be difficult to distinguish in dry bone, an accurate differential diagnosis can be made with careful analysis. [For further reference, see: Ortner 2003: 526, Brothwell 2008: 275, Aufderheide & Rodriguez Martin 1998: 381-382]
Ewing’s sarcoma arises in the medullary cavity, resulting in bone necrosis (tissue death) with non-neoplastic bone formation in thin layers along the cortex. This can produce an “onion peel” effect, and occasionally a “sunburst” effect, similar to that which is seen in osteosarcomas.
Ewing’s sarcoma is often diagnosed in individuals between the ages of 10 and 30. It is commonly found in the long bones of individuals under the age of 20, and in the pelvis, ribs, and vertebrae over the age of 20. Although the location of tumors can be highly variable, the lesions are rarely found in the epiphyseal regions (the ends of long bones). Ewing’s sarcoma usually metastasizes, producing punched-out lesions, primarily in flat bones.
Other conditions with a similar appearance include metastatic carcinoma and osteosarcoma. [For further reference, see: Steinbock 1976: 371-74, Ortner 2003: 526-27, Brothwell 2008: 267, Aufderheide & Rodriquez-Martin 1998: 387-88]
Nasopharyngeal carcinoma is a neoplasm of the head and neck. The tumor originates from the soft tissues of the posterior nasopharynx and aggressively spreads to the palate, sinuses, and orbits. In advanced stages, the cancer may spread through blood, bone marrow metastases.
Important considerations in the differential diagnosis of nasopharyngeal carcinoma are diseases with a similar appearance, such as leprosy, treponemal disease, malignant papilloma, adenocarcinomas of the oral cavity, and localized infection.
Leukemia is the malignant transformation of white blood cells, making the spread of the disease through vascular channels widespread. The white blood cells affected by leukemia are usually dysfunctional and do little to aid the immune system in combating infections. The rapid, mutated development of malignant white blood cells inhibits the formation of normal cells such as platelets, which are essential to preventing hemorrhages.
The major types of leukemia are the acute course, primarily affecting children, and the chronic course, primarily affecting adults. The acute forms of leukemia can generate widely scattered, destructive lesions in both trabecular and cortical bone, whereas chronic leukemia might only present widespread osteoporosis.