Diffuse plexiform neurofibroma with unusual features

TY Raghu, SC Murthy, GR Kanthraj

 Department of Skin and Sexually Transmitted Diseases, Govt. Medical College and Hospitals (V.I.M.S), Bellary-583 104, Karnataka, India

Correspondence Address:
T Y Raghu
Department of Skin and Sexually Transmitted Diseases, Govt. Medical College and Hospitals (V.I.M.S), Bellary-583 104, Karnataka
India

Introduction

Tumour involving nerve trunks of subcutaneous tissue or visceral organs, results in plexiform neurofibromas.[1] It most comonly occurs on the face, cranium, neck and chest and may cause disfigurements.[2] It has been included as one of the diagnostic criterias for neurofibromatosis type I (vor Recklinghausen′s disease). We report a case of plexiform neurofibroma, who had unusual features.

Case Report

A 52-and 15-year-old father and son respectively, presented with asymtomatic papules and plaques over the body [Figure - 1]. The son, born out of a non-consanguineous marriage had a large hyperpigmented, hypertrichotic, loosely hanging tumour, extending from the lower back of left side to the lower end of the knee joint [Figure - 2]. On detailed examination, multiple, small molluscoid tumours were distributed over the right thigh. Multiple small to large cafe-au-lait macules, more than six in number and axillary freckling were present in both of them. Palmar freckling was noticed in father. However, ophthalmic examination revealed, multiple lisch nodules and conjunctival naevus in son, which were conspicuously absent in father. Fundus was normal in both of them. Son recalled rapid increases in size of the swelling since 2-3 years. However, there was no history of deafness, tinnitus, epilepsy, hypertension in both of them. Family history is shown in the pedigree chart [Figure:3]. Further detailed examination revealed a large solitary subcutaneous tumour, soft in consistency, overhanging on itself, with hyperpigmentation and hypertrichosis of the overlying skin. radiographic examination of the area involved by the tumour was normal. Orthopaedic examination revealed genu valgum deformity (synonym : knock knee, which is a deformity marked by abduction of legs in relation to thighs). Routine investigations were normal in both. Ultrasound examination of abdomen of the son revealed splenic hypoechoic lesion suggestive of hamartoma. Summary of findings are illustrated in [Table - 1].

Discussion

A century ago von Recklinghausen[3], described neurofibromatosis in his patients Marie Kientz and Michael Bar. Broadly, It has been divided into neurofibromatosis type I and Type II. Four varieties of neurofibromas have been documented, cutaneous neurofibroma, subcutaneous neurofibroma, nodular plexiform neurofibroma and diffuse plexiform neurofibroma.

In our case, large diffuse plexiform neurofibroma extending from lower back on the left side to the knee joint was present. Diffuse plexiform neurofibroma accounts about 5% of neurofibromatosis type I[4]. The presence of hyperpigmentation and hypertrichosis simulated giant hairy naevus in our case. Orbital and periorbital regions of the face are the commonest sites of involvement[5], however in our case involvement of lower extremity was noticed.

Various skeletal anomalies may occur in neurofibromatosis. Our case, had genu valgum.

Neurofibromas or similar tumours may occur in the bowel, bladder, liver and other viscera, with complications like bleeding obstruction and in our case, we noticed splenic hamartoma, which may be coincidental. Although, plexiform neurofibroma was present since birth, rapid growth was noticed during puberty in our case. Similar accentuation is also noted in pregnancy.[6]

A diffuse plexiform neurofibroma situated over the lower extremity (a rare site), genu valgum deformity, splenic hamartoma were the unusual features in our case. Genetic counselling was done for our patients.

1.	Aloi FG, Massobrio R. Solitary plexiform neurofibroma. Dermatologica 1989; 179:84-86. [Google Scholar]
2.	Short MP, Adams RD. Neurocutaneous diseases, in : Fitzpatrick's Dermatology in General Medicine (Fitzpatrick TB, Eisen AZ, Wolff K, et al. Eds.) Vol-II, 4th edition. New-York: Mcgraw-Hill, Inc., 1993:2259-2263. [Google Scholar]
3.	Von Recklinghausen FD. Ueber die in multiplen Fibrome der Haut and ihre Beziehung zu den multiplen Neuromen. Berlin : Hirschwald; 1882. [Google Scholar]
4.	Pivnick EK, Riccardi VM. The Neurofibromotoses, in : Fitzpatrick's Dermatology in General Medicine (Freedberg IM, Eisen AZ, Wolff K, et al. Eds.) Vol II, 5th edition. New-York : Mcgraw-Hill, 1999 : 2152-2158. [Google Scholar]
5.	Riccardi VM. von Recklinghausen neurofibromatosis. New Engl. 1981; 305:1617-1627. [Google Scholar]
6.	Jarvis GJ, Crompton AC. Neurofibromatosis and pregnancy. Br. J Obstet Gynaecol. 1978; 85:844-846. [Google Scholar]