Primary cutaneous B-cell lymphoma represents a heterogeneous group of entities which show variation in histology, immunophenotype and in prognosis. These are follicular lymphomas, marginal zone B-cell lymphomas and diffuse large B-cell lymphomas
1-3,8. Diffuse large B-cell lymphomas are of the leg type; they manifest in the lower extremity location, and affect elderly patients (mean age 76 years), especially females
1,3,9-11. Diffuse large B-cell lymphomas with leg type is an intermediate-grade B-cell lymphoma that comprises only 1% to 3% of all cutaneous lymphomas and approximately 10% to 20% of primary cutaneous B-cell lymphomas
3.
Primary cutaneous diffuse large B-cell lymphoma, leg type, may show features that overlap with other lymphomas. While a variety of primary cutaneous and systemic/extracutaneous lymphomas may show similar features, the combination of clinical findings, morphology, and immunophenotype helps to distinguish this lymphoma from other diagnostic considerations, with both important prognostic and treatment implications for patients11. Punch (4–6 mm), wedge-incisional, or excisional biopsies are most frequently performed for the diagnosis of primary cutaneous B-cell lymphoma3.
According to their US appearance, the lesions in non-Hodgkin lymphomas of the cutaneous kind are classified as lesions with focal and diffuse patterns. The focal pattern is described as small (0.4-1.8cm), hypoechoic and with well-defined nodules (Type I), or with multiple nodular structures with the same characteristics, which tend to form a polylobulated hypoechoic patchy area (Type II). These lesions are localized in the dermis, in the subcutaneous layer or in both. The diffuse pattern is described as homogeneous hyperechoic thickening of the dermis (Type III) or as diffuse and unhomogeneous infiltrate involving both the dermis and subcutaneous tissue (Type IV)7.
B cell lymphoma can demonstrate nodular and/or diffuse patterns on US. In B-cell lymphomas, solitary or few non-ulcerated regular contoured nodules are together with frequent and early neoplastic lymph node involvement7. Our case presented a mixture of focal and diffuse pattern findings on US and conglomerated LAP US accompanied the picture.
Although the value of CT is limited in cases at an early stage, dermal thickening and subdermal invasion are investigated by CT. In addition to cutaneous lesions, accompanying LAPs are also identified by CT12,13. Miketic12 in none of the 17 stage I cases, and Bass13 in 32 of 43 stage I patients could not identify any describable abnormality by CT. On the CT of our case, in the skin and subdermal tissue with the lesion, there was severe diffuse thickening, a density increase and conglomerated LAP in the femoroinguinal region neighboring this region. Additionally, we identified mediastinal LAP on the thoracal CT of our case.
Magnetic resonance imaging (MRI) with good resolution is clinically advantageous in primary cutaneous lymphomas. MRI can preoperatively evaluate the depth and extension of the primary or recurrent skin tumors14.
Diffuse large B-cell lymphomas are one of the main reasons for the peripheric paralysis of the cranial nerves15. Although recurrences are quite common in the clinical course, extra dermal invasion and internal organ invasion are very rare4. Our case did not have internal organ involvement.
The majority of studies indicate that primary cutaneous B-cell lymphoma is highly responsive to radiotherapy. Polychemotherapy should be reserved for involvement of noncontiguous anatomic sites or those with extracutaneous spread4. There are publications recommending a combination of chemotherapy and radiotherapy as well3,8,10. The prognosis of primary cutaneous B-cell lymphomas is good4,8. Diffuse large B-cell lymphoma, leg type has a poorer prognosis. The 5-year disease-specific survival rates ranged from 43% to 63% in studies3,4.
Although high resolution US has a high sensitivity in skin lymphomas, most of the US patterns are nonspecific and can be found in other dermatological diseases as well. Therefore, the specificity of the US is very low without making a histological examination. However US can be effective in select cases such as cases with suspected lesions and skin lesions that develop following the treatment7. For cases at early stages, CT is of limited value12,13.
In conclusion, for cases that are thought to be cutaneous lymphomas as a result of clinical and radiological investigations, the diagnosis should be confirmed with skin biopsy.