Correct!
1. A prior history of hysterectomy
The history of a severe traumatic episode would raise the possibility of unusual post-traumatic sequelae affecting the thorax, such as splenosis. However, thoracic splenosis most commonly results in nodules affecting the pleural space, not the pulmonary parenchyma, as is the case for this patient. The histopathological findings are consistent with a smooth muscle tumor, but not with a granular cell tumor; furthermore, most granular cell tumors are benign and do not metastasize (rare exceptions are noted). The fact that the chest radiograph shows that the nodules were present 6 years earlier, and largely unchanged for such a long period of time, is highly suggestive of an indolent, benign process. Combining the indolent behavior of the lung nodules with the histopathological data suggesting a smooth muscle tumor makes the history of prior hysterectomy highly significant.
Diagnosis: Benign metastasizing leiomyomas
Discussion: Benign metastasizing leiomyoma is a rare diagnosis. The etiology of this disorder is poorly understood. Some investigators consider benign metastasizing leiomyomas to be low-grade sarcomas metastasizing to the lung, whereas others believe that benign metastasizing leiomyomas represent spread of benign uterine tissue to the lungs via the bloodstream or lymphatics. Benign metastasizing leiomyomas have been reported in other organ systems as well, such as the mesentery, bones, the heart, the central nervous system, and lymph nodes, among other locations.
Almost all cases of benign metastasizing leiomyomas are reported in women with prior histories of uterine leiomyomas who have undergone hysterectomy or myomectomy, although the disorder maybe encountered prior to uterine surgery.
Pulmonary nodules in patients with benign metastasizing leiomyomas may be encountered anywhere from 3 months to 20 years following hysterectomy. Patients are commonly asymptomatic at the time of detection, with thoracic imaging performed for incidental reasons. The clinical course of patients with benign metastasizing leiomyomas is usually indolent. On thoracic imaging studies, the nodules in patients with benign metastasizing leiomyomas are typically circumscribed, either smooth or lobulated, and are usually not calcified. Cystic change is exceptional, as is an interstitial appearance or “miliary” nodules, but these appearances have been reported. Both tracer accumulation and lack of tracer uptake at 18FFDG-PET has been reported in patients with benign metastasizing leiomyomas. The differential diagnostic considerations for the imaging appearance of benign metastasizing leiomyomas are numerous, including metastatic disease, non-infectious inflammatory lesions (such as rheumatoid lung nodules and granulomatosis with polyangiitis), amyloidosis, and infections (typically granulomatous or even parasitic). The diagnosis typically requires the appropriate history of hysterectomy or myomectomy for histologically benign uterine leiomyomas, with tissue sampling of the lesions showing a spindle cell tumor, without necrosis or cellular aytpia, rare or absent mitotic figures, and exclusion of the possibility of sarcoma. Immunochemistry typically shows staining for muscle-specific actin and desmin, and lesion estrogen and progesterone receptor positivity is common.
References